diff --git a/assignment-3/submission/18307130003/README.md b/assignment-3/submission/18307130003/README.md
index 1e2e90a478b7d70794b748bd2676b38172a3004d..7681ef351e62b20db0e897276cca53440388d181 100644
--- a/assignment-3/submission/18307130003/README.md
+++ b/assignment-3/submission/18307130003/README.md
@@ -111,7 +111,7 @@ $$
 我们利用以下函数生成数据集：
 
 ```python {.line-numbers}
-# tester.py
+# source.py
 
 class TestSuite:
     '''
@@ -896,7 +896,7 @@ size = 500
 执行以下指令进行模型的训练与预测。
 
 ```bash
-python ./tester.py
+python ./source.py
 ```
 
 生成数据集使用的参数等可以在 `TestSuite` 类中对应调整。
diff --git a/assignment-3/submission/18307130003/source.py b/assignment-3/submission/18307130003/source.py
index 1f752604c63cda3c2bf4f6483638de95b65dbe5a..8cb42afa5cbcc6d59d6d2afbcb512bb9bb9c069b 100644
--- a/assignment-3/submission/18307130003/source.py
+++ b/assignment-3/submission/18307130003/source.py
@@ -1,15 +1,106 @@
+from typing import Any, Callable, List, NamedTuple, Tuple, Type
+import matplotlib.pyplot as plt
 from abc import ABC, abstractmethod
 import math
 import numpy as np
-from utils import (
-    UniformParameters,
-    assert_,
-    distance,
-    multinormal_pdf,
-    normal_pdf,
-)
 
 
+# Utilities
+
+class NormalParameters(NamedTuple):
+    '''
+    Attributes:
+        `size`: the number of data points in the dataset
+        `mean`: the mean of the distribution
+        `cov`: the coefficient of variation of the distribution (dimension > 1)
+        `scale`: the standard deviation of the distribution (dimension = 1)
+    '''
+
+    size: int
+    mean: Tuple[float, ...]
+    cov: List[List[float]] = None
+    scale: float = None
+
+
+class UniformParameters(NamedTuple):
+    '''
+    Attributes:
+        `size`: the number of data points in the dataset
+        `intervals`: the range of each dimension, Tuple[shape(N), shape(N)]
+    '''
+
+    size: int
+    intervals: Tuple[np.ndarray, np.ndarray]
+
+
+def distance(point_1: np.ndarray, point_2: np.ndarray) -> float:
+    '''
+    Args:
+        `point_1`: shape(d)
+        `point_2`: shape(d)
+
+    Return:
+        The Euclidean distance between two points.
+    '''
+
+    return np.linalg.norm(point_1 - point_2)
+
+
+def multinormal_pdf(x: np.ndarray, mean: np.ndarray, cov: np.ndarray) -> float:
+    '''
+    The probability density function of a multivariate Gaussian distribution
+    with given parameters.
+
+    Args:
+        `x`: an observation, shape(d)
+        `mean`: the mean of the distribution, shape(d)
+        `cov`: the coefficient of variation of the distribution, shape(d, d)
+
+    Return:
+        f(x | mean, cov)
+    '''
+
+    cov_det: float = np.linalg.det(cov)
+    dim: int = mean.shape[0]
+    const: float = (((2 * math.pi) ** dim) * cov_det) ** (-1/2)
+    x_m: np.ndarray = x - mean
+    exp: float = -np.dot(x_m, np.linalg.solve(cov, x_m)) / 2
+    return const * math.exp(exp)
+
+
+def normal_pdf(x: float, mean: float, scale: float) -> float:
+    '''
+    The probability density function of a Gaussian distribution with given
+    parameters.
+
+    Args:
+        `x`: an observation
+        `mean`: the mean of the distribution
+        `scale`: the standard deviation of the distribution
+
+    Return:
+        f(x | mean, scale)
+    '''
+
+    const = (2 * math.pi) ** (-1/2) / scale
+    exp = -((x - mean) / scale) ** 2 / 2
+    return const * math.exp(exp)
+
+
+def assert_(var_name: str, got: Any, expected: Any) -> None:
+    '''
+    Args:
+        `var_name`: variable name for logging
+        `got`: actual value
+        `expected`: expected value
+    '''
+
+    message = f'Assertion failed for {var_name}: expected {expected}, got {got}'
+    assert got == expected, message
+
+
+# Models
+
 class Model(ABC):
     '''
     The abstract class (ABC) of a model.
@@ -150,9 +241,9 @@ class KMeans(Model):
 
 class GaussianMixture(Model):
     '''
-    Gaussian Mixture Model (GMM) is a probabilistic model that assumes there
+    Gaussian Mixture Model (GaussianMixture) is a probabilistic model that assumes there
     are a certain number of Gaussian distributions, and each of these
-    distributions represent a cluster. Hence, a GMM tends to group the data
+    distributions represent a cluster. Hence, a GaussianMixture tends to group the data
     points belonging to a single distribution together.
     '''
 
@@ -471,3 +562,341 @@ class ClusteringAlgorithm(Model):
     def predict(self, test_data: np.ndarray) -> np.ndarray:
 
         return self.best_model.predict(test_data)
+
+
+# Tester
+
+class TestSuite:
+    '''
+    Multiple testing data for models.
+    '''
+
+    def __init__(self) -> None:
+        self.rng: np.random.Generator = np.random.default_rng()
+
+    def generate_normal(self, param: NormalParameters) -> np.ndarray:
+        '''
+        Generate a dataset from a Gaussian distribution with given parameters.
+
+        Args:
+            `param`: parameters used to generate a dataset
+
+        Return:
+            shape(N, d)
+        '''
+
+        size, mean, cov, scale = param
+        if len(mean) > 1:
+            return self.rng.multivariate_normal(mean, cov, size)
+        else:
+            return self.rng.normal(mean[0], scale, size)
+
+    def combine(self, *datasets: np.ndarray) -> Tuple[np.ndarray, np.ndarray]:
+        '''
+        Combine several datasets into a single dataset.
+
+        Args:
+            `*datasets`: a tuple of datasets needed to combine
+
+        Return:
+            `dataset`: shape(N, d), where N is the total size of all datasets
+            `labels`: shape(N), the labels for all points in the dataset
+        '''
+
+        dataset: np.ndarray = np.concatenate(datasets)
+        labels: np.ndarray = np.concatenate([
+            np.ones(d.shape[0], dtype=int) * i
+            for (i, d) in enumerate(datasets)
+        ])
+        indices = np.arange(dataset.shape[0])
+        np.random.shuffle(indices)
+        dataset = dataset[indices]
+        labels = labels[indices]
+        return dataset, labels
+
+    def generate_data(self, *params: NormalParameters) -> Tuple[np.ndarray, int]:
+        '''
+        Generate a dataset for tests.
+
+        Args:
+            `params`: a tuple of parameters to generate datasets
+
+        Return:
+            `dataset`: shape(N, d)
+            `n_clusters`: the number of clusters to partition into
+        '''
+
+        dataset, _labels = self.combine(*tuple(
+            self.generate_normal(p) for p in params
+        ))
+        n_clusters: int = len(params)
+        return dataset, n_clusters
+
+    def train(
+        self, train_data: np.ndarray, model: Model
+    ) -> Tuple[np.ndarray, np.ndarray, np.ndarray]:
+        '''
+        Train a model with training data.
+
+        Args:
+            `train_data`: shape(N, d)
+            `model`: the model that we need to train
+            `n_clusters`: the number of clusters to partition into
+
+        Return:
+            `train_labels`: the predicted labels of training data, shape(N)
+            `centroids`: the centroids calculated from training data, shape(k, d)
+            `gaps`: the gap statistics of each k, shape(k + 1)
+        '''
+
+        model.fit(train_data)
+        train_labels = model.predict(train_data)
+        centroids: np.ndarray = None
+        gaps: np.ndarray = None
+
+        if isinstance(model, KMeans):
+            centroids = model.centroids
+        elif isinstance(model, GaussianMixture):
+            centroids = model.means
+        elif isinstance(model, ClusteringAlgorithm):
+            centroids = model.best_model.centroids
+            gaps = model.gaps
+        return train_labels, centroids, gaps
+
+    def evaluate(self, test_data: np.ndarray, model: Model) -> Tuple[np.ndarray]:
+        '''
+        Evaluate a model with testing data.
+
+        Args:
+            `test_data`: shape(N, d)
+            `model`: the model that we need to evaluate
+
+        Return:
+            `test_labels`: The predicted labels of testing data, shape(N)
+        '''
+
+        test_labels = model.predict(test_data)
+        return test_labels
+
+    def test_data_1(self) -> Tuple[np.ndarray, int]:
+
+        return self.generate_data(
+            NormalParameters(
+                size=800,
+                mean=(1, 2),
+                cov=[[73, 0], [0, 22]],
+            ),
+            NormalParameters(
+                size=200,
+                mean=(16, -5),
+                cov=[[21.2, 0], [0, 32.1]],
+            ),
+            NormalParameters(
+                size=1000,
+                mean=(10, 22),
+                cov=[[10, 5], [5, 10]],
+            ),
+        )
+
+    def test_data_2(self) -> Tuple[np.ndarray, int]:
+
+        return self.generate_data(
+            NormalParameters(
+                size=800,
+                mean=(1, 0),
+                cov=[[73, 0], [0, 22]],
+            ),
+            NormalParameters(
+                size=400,
+                mean=(20, 15),
+                cov=[[21.2, 0], [0, 32.1]],
+            ),
+            NormalParameters(
+                size=1000,
+                mean=(10, -22),
+                cov=[[10, 5], [5, 10]],
+            ),
+            NormalParameters(
+                size=500,
+                mean=(-12, -6),
+                cov=[[7, 3], [3, 16]],
+            ),
+            NormalParameters(
+                size=600,
+                mean=(-15, 17),
+                cov=[[15, 0], [0, 12]],
+            ),
+        )
+
+    def test_data_3(self) -> Tuple[np.ndarray, int]:
+
+        return self.generate_data(
+            NormalParameters(
+                size=800,
+                mean=(-6, 3, 5),
+                cov=[[73, 0, 0], [0, 50, 0], [0, 0, 22]],
+            ),
+            NormalParameters(
+                size=500,
+                mean=(12, 0, -10),
+                cov=[[20, 5, 0], [5, 20, 0], [0, 0, 20]],
+            ),
+            NormalParameters(
+                size=800,
+                mean=(10, -20, 0),
+                cov=[[10, 1, 3], [1, 10, 0], [3, 0, 10]],
+            ),
+        )
+
+    def test_data_4(self) -> Tuple[np.ndarray, int]:
+
+        return self.generate_data(
+            NormalParameters(
+                size=100,
+                mean=(-20,),
+                scale=2,
+            ),
+            NormalParameters(
+                size=150,
+                mean=(0,),
+                scale=1,
+            ),
+            NormalParameters(
+                size=100,
+                mean=(15,),
+                scale=2,
+            ),
+        )
+
+    def test_data_5(self) -> Tuple[np.ndarray, int]:
+
+        return self.generate_data(
+            NormalParameters(
+                size=800,
+                mean=(0, -5),
+                cov=[[73, 0], [0, 2]],
+            ),
+            NormalParameters(
+                size=500,
+                mean=(-3, 0),
+                cov=[[100, 0], [0, 2]],
+            ),
+            NormalParameters(
+                size=500,
+                mean=(2, 5),
+                cov=[[70, 1], [1, 3]],
+            ),
+        )
+
+    def run(self) -> None:
+        '''
+        Run all the tests.
+        '''
+
+        testcases: List[Tuple[
+            str, Callable[[], Tuple[np.ndarray, int]], Type[Model], int
+        ]] = [
+            ('k-means_1', self.test_data_1, KMeans, 0),
+            # ('k-means_2', self.test_data_2, KMeans, 0),
+            # ('k-means_3', self.test_data_3, KMeans, 0),
+            # ('k-means_4', self.test_data_4, KMeans, 0),
+            # ('k-means_5', self.test_data_5, KMeans, 0),
+            # ('GaussianMixture_1', self.test_data_1, GaussianMixture, 0),
+            # ('GaussianMixture_2', self.test_data_2, GaussianMixture, 0),
+            # ('GaussianMixture_3', self.test_data_3, GaussianMixture, 0),
+            # ('GaussianMixture_4', self.test_data_4, GaussianMixture, 0),
+            # ('GaussianMixture_5', self.test_data_5, GaussianMixture, 0),
+            # ('auto-k-means_1', self.test_data_1, ClusteringAlgorithm, 10),
+            # ('auto-k-means_2', self.test_data_2, ClusteringAlgorithm, 10),
+            # ('auto-k-means_3', self.test_data_3, ClusteringAlgorithm, 10),
+            # ('auto-k-means_4', self.test_data_4, ClusteringAlgorithm, 10),
+            # ('auto-k-means_5', self.test_data_5, ClusteringAlgorithm, 10),
+        ]
+
+        for testcase in testcases:
+            name, get_dataset, model_class, n_clusters = testcase
+
+            # Obtain training data and testing data
+            dataset, real_n_clusters = get_dataset()
+            train_size: int = math.floor(dataset.shape[0] * 0.8)
+            train_data: np.ndarray = dataset[:train_size]
+            test_data: np.ndarray = dataset[train_size:]
+
+            # Train the model with training data
+            model = model_class(n_clusters or real_n_clusters)
+            train_labels, centroids, gaps = self.train(train_data, model)
+
+            # Evaluate the model with testing data
+            test_labels = self.evaluate(test_data, model)
+
+            # Visualize the datasets with labels
+            visualize(name + '_train', train_data, train_labels, centroids)
+            visualize(name + '_test', test_data, test_labels, centroids)
+
+            # Visualize the gap statistics for
+            if gaps is not None:
+                visualize_gaps(name + '_gaps', gaps)
+
+            print(f'{name}: Done.')
+
+
+def visualize(
+    name: str,
+    dataset: np.ndarray,
+    labels: np.ndarray,
+    centroids: np.ndarray = None,
+) -> None:
+    '''
+    Visualize a dataset with labels.
+
+    Args:
+        `name`: the output filename when saving the figure
+        `dataset`: shape(N, d)
+        `labels`: shape(N)
+        `centroids`: shape(k, d)
+    '''
+
+    assert_('dataset.shape[0]', dataset.shape[0], labels.shape[0])
+
+    # Plot the data points and the centroids.
+    if len(dataset.shape) > 1:
+        plt.scatter(dataset[:, 0], dataset[:, 1], c=labels, s=30)
+        if centroids is not None:
+            plt.scatter(
+                centroids[:, 0], centroids[:, 1], c='black', s=100, alpha=0.5,
+            )
+    else:
+        plt.scatter(dataset, np.zeros(dataset.shape[0]), c=labels, s=30)
+        if centroids is not None:
+            plt.yticks([])
+            plt.scatter(
+                centroids, np.zeros(centroids.shape[0]),
+                c='black', s=100, alpha=0.5,
+            )
+
+    # Save the figure to a local file.
+    plt.savefig(f'img/{name}')
+    plt.clf()
+
+
+def visualize_gaps(name: str, gaps: np.ndarray) -> None:
+    '''
+    Visualize the gap statistics.
+
+    Args:
+        `name`: the output filename when saving the figure
+        `gaps`: the gap statistics of each k, shape(k + 1)
+    '''
+
+    # Plot the gap statistics.
+    indices = np.arange(1, gaps.shape[0], dtype=int)
+    plt.xticks(indices)
+    plt.plot(indices, gaps[indices], '-bo')
+
+    # Save the figure to a local file.
+    plt.savefig(f'img/{name}')
+    plt.clf()
+
+
+if __name__ == '__main__':
+    TestSuite().run()
diff --git a/assignment-3/submission/18307130003/tester.py b/assignment-3/submission/18307130003/tester.py
deleted file mode 100644
index c2c14ae7279129374d28952c711324a4d0dffa4e..0000000000000000000000000000000000000000
--- a/assignment-3/submission/18307130003/tester.py
+++ /dev/null
@@ -1,347 +0,0 @@
-from typing import Callable, List, Tuple, Type
-import math
-import numpy as np
-import matplotlib.pyplot as plt
-from source import (
-    ClusteringAlgorithm as AutoKMeans,
-    Model,
-    KMeans,
-    GaussianMixture as GMM,
-)
-from utils import assert_, NormalParameters
-
-
-class TestSuite:
-    '''
-    Multiple testing data for models.
-    '''
-
-    def __init__(self) -> None:
-        self.rng: np.random.Generator = np.random.default_rng()
-
-    def generate_normal(self, param: NormalParameters) -> np.ndarray:
-        '''
-        Generate a dataset from a Gaussian distribution with given parameters.
-
-        Args:
-            `param`: parameters used to generate a dataset
-
-        Return:
-            shape(N, d)
-        '''
-
-        size, mean, cov, scale = param
-        if len(mean) > 1:
-            return self.rng.multivariate_normal(mean, cov, size)
-        else:
-            return self.rng.normal(mean[0], scale, size)
-
-    def combine(self, *datasets: np.ndarray) -> Tuple[np.ndarray, np.ndarray]:
-        '''
-        Combine several datasets into a single dataset.
-
-        Args:
-            `*datasets`: a tuple of datasets needed to combine
-
-        Return:
-            `dataset`: shape(N, d), where N is the total size of all datasets
-            `labels`: shape(N), the labels for all points in the dataset
-        '''
-
-        dataset: np.ndarray = np.concatenate(datasets)
-        labels: np.ndarray = np.concatenate([
-            np.ones(d.shape[0], dtype=int) * i
-            for (i, d) in enumerate(datasets)
-        ])
-        indices = np.arange(dataset.shape[0])
-        np.random.shuffle(indices)
-        dataset = dataset[indices]
-        labels = labels[indices]
-        return dataset, labels
-
-    def generate_data(self, *params: NormalParameters) -> Tuple[np.ndarray, int]:
-        '''
-        Generate a dataset for tests.
-
-        Args:
-            `params`: a tuple of parameters to generate datasets
-
-        Return:
-            `dataset`: shape(N, d)
-            `n_clusters`: the number of clusters to partition into
-        '''
-
-        dataset, _labels = self.combine(*tuple(
-            self.generate_normal(p) for p in params
-        ))
-        n_clusters: int = len(params)
-        return dataset, n_clusters
-
-    def train(
-        self, train_data: np.ndarray, model: Model
-    ) -> Tuple[np.ndarray, np.ndarray, np.ndarray]:
-        '''
-        Train a model with training data.
-
-        Args:
-            `train_data`: shape(N, d)
-            `model`: the model that we need to train
-            `n_clusters`: the number of clusters to partition into
-
-        Return:
-            `train_labels`: the predicted labels of training data, shape(N)
-            `centroids`: the centroids calculated from training data, shape(k, d)
-            `gaps`: the gap statistics of each k, shape(k + 1)
-        '''
-
-        model.fit(train_data)
-        train_labels = model.predict(train_data)
-        centroids: np.ndarray = None
-        gaps: np.ndarray = None
-
-        if isinstance(model, KMeans):
-            centroids = model.centroids
-        elif isinstance(model, GMM):
-            centroids = model.means
-        elif isinstance(model, AutoKMeans):
-            centroids = model.best_model.centroids
-            gaps = model.gaps
-        return train_labels, centroids, gaps
-
-    def evaluate(self, test_data: np.ndarray, model: Model) -> Tuple[np.ndarray]:
-        '''
-        Evaluate a model with testing data.
-
-        Args:
-            `test_data`: shape(N, d)
-            `model`: the model that we need to evaluate
-
-        Return:
-            `test_labels`: The predicted labels of testing data, shape(N)
-        '''
-
-        test_labels = model.predict(test_data)
-        return test_labels
-
-    def test_data_1(self) -> Tuple[np.ndarray, int]:
-
-        return self.generate_data(
-            NormalParameters(
-                size=800,
-                mean=(1, 2),
-                cov=[[73, 0], [0, 22]],
-            ),
-            NormalParameters(
-                size=200,
-                mean=(16, -5),
-                cov=[[21.2, 0], [0, 32.1]],
-            ),
-            NormalParameters(
-                size=1000,
-                mean=(10, 22),
-                cov=[[10, 5], [5, 10]],
-            ),
-        )
-
-    def test_data_2(self) -> Tuple[np.ndarray, int]:
-
-        return self.generate_data(
-            NormalParameters(
-                size=800,
-                mean=(1, 0),
-                cov=[[73, 0], [0, 22]],
-            ),
-            NormalParameters(
-                size=400,
-                mean=(20, 15),
-                cov=[[21.2, 0], [0, 32.1]],
-            ),
-            NormalParameters(
-                size=1000,
-                mean=(10, -22),
-                cov=[[10, 5], [5, 10]],
-            ),
-            NormalParameters(
-                size=500,
-                mean=(-12, -6),
-                cov=[[7, 3], [3, 16]],
-            ),
-            NormalParameters(
-                size=600,
-                mean=(-15, 17),
-                cov=[[15, 0], [0, 12]],
-            ),
-        )
-
-    def test_data_3(self) -> Tuple[np.ndarray, int]:
-
-        return self.generate_data(
-            NormalParameters(
-                size=800,
-                mean=(-6, 3, 5),
-                cov=[[73, 0, 0], [0, 50, 0], [0, 0, 22]],
-            ),
-            NormalParameters(
-                size=500,
-                mean=(12, 0, -10),
-                cov=[[20, 5, 0], [5, 20, 0], [0, 0, 20]],
-            ),
-            NormalParameters(
-                size=800,
-                mean=(10, -20, 0),
-                cov=[[10, 1, 3], [1, 10, 0], [3, 0, 10]],
-            ),
-        )
-
-    def test_data_4(self) -> Tuple[np.ndarray, int]:
-
-        return self.generate_data(
-            NormalParameters(
-                size=100,
-                mean=(-20,),
-                scale=2,
-            ),
-            NormalParameters(
-                size=150,
-                mean=(0,),
-                scale=1,
-            ),
-            NormalParameters(
-                size=100,
-                mean=(15,),
-                scale=2,
-            ),
-        )
-
-    def test_data_5(self) -> Tuple[np.ndarray, int]:
-
-        return self.generate_data(
-            NormalParameters(
-                size=800,
-                mean=(0, -5),
-                cov=[[73, 0], [0, 2]],
-            ),
-            NormalParameters(
-                size=500,
-                mean=(-3, 0),
-                cov=[[100, 0], [0, 2]],
-            ),
-            NormalParameters(
-                size=500,
-                mean=(2, 5),
-                cov=[[70, 1], [1, 3]],
-            ),
-        )
-
-    def run(self) -> None:
-        '''
-        Run all the tests.
-        '''
-
-        testcases: List[Tuple[
-            str, Callable[[], Tuple[np.ndarray, int]], Type[Model], int
-        ]] = [
-            ('k-means_1', self.test_data_1, KMeans, 0),
-            ('k-means_2', self.test_data_2, KMeans, 0),
-            ('k-means_3', self.test_data_3, KMeans, 0),
-            ('k-means_4', self.test_data_4, KMeans, 0),
-            ('k-means_5', self.test_data_5, KMeans, 0),
-            ('gmm_1', self.test_data_1, GMM, 0),
-            ('gmm_2', self.test_data_2, GMM, 0),
-            ('gmm_3', self.test_data_3, GMM, 0),
-            ('gmm_4', self.test_data_4, GMM, 0),
-            ('gmm_5', self.test_data_5, GMM, 0),
-            ('auto-k-means_1', self.test_data_1, AutoKMeans, 10),
-            ('auto-k-means_2', self.test_data_2, AutoKMeans, 10),
-            ('auto-k-means_3', self.test_data_3, AutoKMeans, 10),
-            ('auto-k-means_4', self.test_data_4, AutoKMeans, 10),
-            ('auto-k-means_5', self.test_data_5, AutoKMeans, 10),
-        ]
-
-        for testcase in testcases:
-            name, get_dataset, model_class, n_clusters = testcase
-
-            # Obtain training data and testing data
-            dataset, real_n_clusters = get_dataset()
-            train_size: int = math.floor(dataset.shape[0] * 0.8)
-            train_data: np.ndarray = dataset[:train_size]
-            test_data: np.ndarray = dataset[train_size:]
-
-            # Train the model with training data
-            model = model_class(n_clusters or real_n_clusters)
-            train_labels, centroids, gaps = self.train(train_data, model)
-
-            # Evaluate the model with testing data
-            test_labels = self.evaluate(test_data, model)
-
-            # Visualize the datasets with labels
-            visualize(name + '_train', train_data, train_labels, centroids)
-            visualize(name + '_test', test_data, test_labels, centroids)
-
-            # Visualize the gap statistics for
-            if gaps is not None:
-                visualize_gaps(name + '_gaps', gaps)
-
-            print(f'{name}: Done.')
-
-
-def visualize(
-    name: str,
-    dataset: np.ndarray,
-    labels: np.ndarray,
-    centroids: np.ndarray = None,
-) -> None:
-    '''
-    Visualize a dataset with labels.
-
-    Args:
-        `name`: the output filename when saving the figure
-        `dataset`: shape(N, d)
-        `labels`: shape(N)
-        `centroids`: shape(k, d)
-    '''
-
-    assert_('dataset.shape[0]', dataset.shape[0], labels.shape[0])
-
-    # Plot the data points and the centroids.
-    if len(dataset.shape) > 1:
-        plt.scatter(dataset[:, 0], dataset[:, 1], c=labels, s=30)
-        if centroids is not None:
-            plt.scatter(
-                centroids[:, 0], centroids[:, 1], c='black', s=100, alpha=0.5,
-            )
-    else:
-        plt.scatter(dataset, np.zeros(dataset.shape[0]), c=labels, s=30)
-        if centroids is not None:
-            plt.yticks([])
-            plt.scatter(
-                centroids, np.zeros(centroids.shape[0]),
-                c='black', s=100, alpha=0.5,
-            )
-
-    # Save the figure to a local file.
-    plt.savefig(f'img/{name}')
-    plt.clf()
-
-
-def visualize_gaps(name: str, gaps: np.ndarray) -> None:
-    '''
-    Visualize the gap statistics.
-
-    Args:
-        `name`: the output filename when saving the figure
-        `gaps`: the gap statistics of each k, shape(k + 1)
-    '''
-
-    # Plot the gap statistics.
-    indices = np.arange(1, gaps.shape[0], dtype=int)
-    plt.xticks(indices)
-    plt.plot(indices, gaps[indices], '-bo')
-
-    # Save the figure to a local file.
-    plt.savefig(f'img/{name}')
-    plt.clf()
-
-
-if __name__ == '__main__':
-    TestSuite().run()
diff --git a/assignment-3/submission/18307130003/utils.py b/assignment-3/submission/18307130003/utils.py
deleted file mode 100644
index 37d82a1dace1a13fe0e409842b99ea1756ef4547..0000000000000000000000000000000000000000
--- a/assignment-3/submission/18307130003/utils.py
+++ /dev/null
@@ -1,95 +0,0 @@
-from typing import Any, List, NamedTuple, Tuple
-import numpy as np
-import math
-
-
-class NormalParameters(NamedTuple):
-    '''
-    Attributes:
-        `size`: the number of data points in the dataset
-        `mean`: the mean of the distribution
-        `cov`: the coefficient of variation of the distribution (dimension > 1)
-        `scale`: the standard deviation of the distribution (dimension = 1)
-    '''
-
-    size: int
-    mean: Tuple[float, ...]
-    cov: List[List[float]] = None
-    scale: float = None
-
-
-class UniformParameters(NamedTuple):
-    '''
-    Attributes:
-        `size`: the number of data points in the dataset
-        `intervals`: the range of each dimension, Tuple[shape(N), shape(N)]
-    '''
-
-    size: int
-    intervals: Tuple[np.ndarray, np.ndarray]
-
-
-def distance(point_1: np.ndarray, point_2: np.ndarray) -> float:
-    '''
-    Args:
-        `point_1`: shape(d)
-        `point_2`: shape(d)
-
-    Return:
-        The Euclidean distance between two points.
-    '''
-
-    return np.linalg.norm(point_1 - point_2)
-
-
-def multinormal_pdf(x: np.ndarray, mean: np.ndarray, cov: np.ndarray) -> float:
-    '''
-    The probability density function of a multivariate Gaussian distribution
-    with given parameters.
-
-    Args:
-        `x`: an observation, shape(d)
-        `mean`: the mean of the distribution, shape(d)
-        `cov`: the coefficient of variation of the distribution, shape(d, d)
-
-    Return:
-        f(x | mean, cov)
-    '''
-
-    cov_det: float = np.linalg.det(cov)
-    dim: int = mean.shape[0]
-    const: float = (((2 * math.pi) ** dim) * cov_det) ** (-1/2)
-    x_m: np.ndarray = x - mean
-    exp: float = -np.dot(x_m, np.linalg.solve(cov, x_m)) / 2
-    return const * math.exp(exp)
-
-
-def normal_pdf(x: float, mean: float, scale: float) -> float:
-    '''
-    The probability density function of a Gaussian distribution with given
-    parameters.
-
-    Args:
-        `x`: an observation
-        `mean`: the mean of the distribution
-        `scale`: the standard deviation of the distribution
-
-    Return:
-        f(x | mean, scale)
-    '''
-
-    const = (2 * math.pi) ** (-1/2) / scale
-    exp = -((x - mean) / scale) ** 2 / 2
-    return const * math.exp(exp)
-
-
-def assert_(var_name: str, got: Any, expected: Any) -> None:
-    '''
-    Args:
-        `var_name`: variable name for logging
-        `got`: actual value
-        `expected`: expected value
-    '''
-
-    message = f'Assertion failed for {var_name}: expected {expected}, got {got}'
-    assert got == expected, message