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Assignment 2 #2

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Mar 4, 2025
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Assignment 2 #2

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b7028d8
assignment_1
k2jac9 Feb 17, 2025
3fd4497
assignment_2
k2jac9 Feb 20, 2025
ae08fc9
assignment_2 PDF
k2jac9 Feb 24, 2025
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262 changes: 221 additions & 41 deletions 02_activities/assignments/assignment_1.ipynb
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Original file line number Diff line number Diff line change
Expand Up @@ -21,19 +21,27 @@
},
{
"cell_type": "code",
"execution_count": null,
"execution_count": 1,
"metadata": {},
"outputs": [],
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"3\n"
]
}
],
"source": [
"import hashlib\n",
"\n",
"def hash_to_range(input_string: str) -> int:\n",
" hash_object = hashlib.sha256(input_string.encode())\n",
" hash_int = int(hash_object.hexdigest(), 16)\n",
" return (hash_int % 3) + 1\n",
"input_string = \"your_first_name_here\"\n",
"input_string = \"alejandro castellanos\"\n",
"result = hash_to_range(input_string)\n",
"print(result)\n"
"print(result) # Output: 3\n"
]
},
{
Expand Down Expand Up @@ -80,7 +88,7 @@
},
{
"cell_type": "code",
"execution_count": null,
"execution_count": 2,
"metadata": {},
"outputs": [],
"source": [
Expand All @@ -90,8 +98,7 @@
"# self.val = val\n",
"# self.left = left\n",
"# self.right = right\n",
"def is_duplicate(root: TreeNode) -> int:\n",
" # TODO"
"# def is_duplicate(root: TreeNode) -> int:\n"
]
},
{
Expand Down Expand Up @@ -130,7 +137,7 @@
},
{
"cell_type": "code",
"execution_count": null,
"execution_count": 3,
"metadata": {},
"outputs": [],
"source": [
Expand All @@ -140,8 +147,7 @@
"# self.val = val\n",
"# self.left = left\n",
"# self.right = right\n",
"def bt_path(root: TreeNode) -> List[List[int]]:\n",
" # TODO"
"# def bt_path(root: TreeNode) -> List[List[int]]:\n"
]
},
{
Expand Down Expand Up @@ -180,49 +186,152 @@
"#### Starter Code for Question 3\n"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"### Solving for missing numbers within the valid range"
]
},
{
"cell_type": "code",
"execution_count": null,
"execution_count": 4,
"metadata": {},
"outputs": [],
"source": [
"def missing_num(nums: List) -> int:\n",
" # TODO"
"def missing_num(nums):\n",
" # Find the largest number in the list\n",
" n = max(nums) # The largest number should be the upper bound\n",
" \n",
" # Create a set of the numbers in the list (automatically removes duplicates)\n",
" num_set = set(nums)\n",
" \n",
" # Generate the list of missing numbers\n",
" missing = [i for i in range(n + 1) if i not in num_set]\n",
" \n",
" # If no numbers are missing, return -1\n",
" if not missing:\n",
" return -1\n",
" \n",
" return missing\n",
"\n"
]
},
{
"cell_type": "code",
"execution_count": 5,
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"-1\n",
"-1\n",
"[1]\n",
"[2, 3, 4]\n",
"[4, 9]\n"
]
}
],
"source": [
"print(missing_num([0])) # Output: -1\n",
"print(missing_num([0, 1])) # Output: -1\n",
"print(missing_num([0, 2])) # Output: [1]\n",
"print(missing_num([5, 0, 1])) # Output: [2, 3, 4]\n",
"print(missing_num([6, 8, 2, 3, 5, 7, 0, 1, 10])) # Output: [4, 9]"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"\n",
"## Part 2:\n",
"\n",
"- Paraphrase the problem in your own words\n"
"### Importing List from typing"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"### Solving for missing numbers within the valid range"
]
},
{
"cell_type": "code",
"execution_count": null,
"execution_count": 6,
"metadata": {},
"outputs": [],
"source": [
"# Your answer here"
"from typing import List # Import List from typing module\n",
"\n",
"def missing_num(nums: List[int]) -> int:\n",
" # Find the largest number in the list\n",
" n = max(nums) # The largest number should be the upper bound\n",
" \n",
" # Create a set of the numbers in the list (automatically removes duplicates)\n",
" num_set = set(nums)\n",
" \n",
" # Generate the list of missing numbers\n",
" missing = [i for i in range(n + 1) if i not in num_set]\n",
" \n",
" # If no numbers are missing, return -1\n",
" if not missing:\n",
" return -1\n",
" \n",
" return missing\n"
]
},
{
"cell_type": "code",
"execution_count": 7,
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"-1\n",
"-1\n",
"[1]\n",
"[2, 3, 4]\n",
"[4, 9]\n"
]
}
],
"source": [
"print(missing_num([0])) # Output: -1\n",
"print(missing_num([0, 1])) # Output: -1\n",
"print(missing_num([0, 2])) # Output: [1]\n",
"print(missing_num([5, 0, 1])) # Output: [2, 3, 4]\n",
"print(missing_num([6, 8, 2, 3, 5, 7, 0, 1, 10])) # Output: [4, 9]\n"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"- In this .ipynb file, there are examples that illustrate how the code should work (the examples provided above). Create 2 new examples for the question you have been assigned, that demonstrate you understand the problem. For question 1 and 2, you don't need to create the tree demonstration, just the input and output.\n"
"\n",
"## Part 2:\n",
"\n",
"- Paraphrase the problem in your own words\n"
]
},
{
"cell_type": "code",
"execution_count": null,
"cell_type": "markdown",
"metadata": {},
"outputs": [],
"source": [
"# Your answer here"
"We have a list of numbers that should cover all integers from 0 to n, but some numbers may be missing or repeated. The task is to find which numbers are missing from the list.\n",
"\n",
"We need to identify which numbers are missing in the range from 0 to the maximum number in the list. If no numbers are missing, we return -1.\n",
"\n",
"This problem is about finding which numbers are missing from a list that should contain all integers from 0 to the maximum number. By using a set to remove duplicates and a list comprehension to find missing numbers, we can solve this efficiently.\n"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"- In this .ipynb file, there are examples that illustrate how the code should work (the examples provided above). Create 2 new examples for the question you have been assigned, that demonstrate you understand the problem. For question 1 and 2, you don't need to create the tree demonstration, just the input and output.\n"
]
},
{
Expand All @@ -235,11 +344,52 @@
},
{
"cell_type": "code",
"execution_count": null,
"execution_count": 8,
"metadata": {},
"outputs": [],
"source": [
"# Your answer here"
"from typing import List\n",
"\n",
"def missing_num(nums: List[int]) -> int:\n",
" # Step 1: Find the maximum number in the list\n",
" n = max(nums)\n",
" \n",
" # Step 2: Create a set of all numbers from 0 to n\n",
" full_set = set(range(n + 1))\n",
" \n",
" # Step 3: Create a set from the input list\n",
" num_set = set(nums)\n",
" \n",
" # Step 4: Find the missing numbers\n",
" missing = list(full_set - num_set)\n",
" \n",
" # Step 5: Return the missing numbers or -1 if there are none\n",
" return missing if missing else -1\n"
]
},
{
"cell_type": "code",
"execution_count": 9,
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"[2, 3, 4]\n",
"[1]\n",
"[1, 3, 6]\n",
"-1\n",
"-1\n"
]
}
],
"source": [
"print(missing_num([5, 0, 1])) # Output: [2, 3, 4]\n",
"print(missing_num([0, 2, 2])) # Output: [1]\n",
"print(missing_num([8, 2, 0, 5, 7, 7, 4])) # Output: [1, 3, 6]\n",
"print(missing_num([0, 1])) # Output: -1\n",
"print(missing_num([0])) # Output: -1"
]
},
{
Expand All @@ -251,12 +401,18 @@
]
},
{
"cell_type": "code",
"execution_count": null,
"cell_type": "markdown",
"metadata": {},
"outputs": [],
"source": [
"# Your answer here"
"Explanation:\n",
"\n",
"Full Set (full_set): This set contains all the numbers from 0 to the maximum number in the list (n).\n",
"\n",
"Input Set (num_set): We create a set from the input list to remove duplicates.\n",
"\n",
"Missing Numbers: By subtracting num_set from full_set, we get the missing numbers. \n",
"\n",
"If there are no missing numbers, we return -1."
]
},
{
Expand All @@ -268,12 +424,14 @@
]
},
{
"cell_type": "code",
"execution_count": null,
"cell_type": "markdown",
"metadata": {},
"outputs": [],
"source": [
"# Your answer here"
"Time and Space Complexity:\n",
"\n",
"Time Complexity: O(n), where n is the length of the input list. We iterate over the list twice (once to create the set and once to subtract the sets).\n",
"\n",
"Space Complexity: O(n), for the sets (full_set and num_set) used to store the numbers."
]
},
{
Expand All @@ -285,12 +443,34 @@
]
},
{
"cell_type": "code",
"execution_count": null,
"cell_type": "markdown",
"metadata": {},
"outputs": [],
"source": [
"# Your answer here"
"Alternative Approach: Using a Boolean Array (Frequency Array) to Track Presence\n",
"\n",
"Determine the Range:\n",
"\n",
"First, find the maximum value in the input list. This value (let's call it max_value) represents the highest number we expect in the complete range from 0 to max_value.\n",
"Initialize a Boolean Array:\n",
"\n",
"Create a boolean array (or list) called seen with a length of max_value + 1.\n",
"Initialize every element to False. This array will track which numbers have been encountered.\n",
"Mark the Numbers Present:\n",
"\n",
"Iterate through the input list.\n",
"For each number num in the list, set seen[num] to True (this marks that the number num is present in the list).\n",
"Identify Missing Numbers:\n",
"\n",
"Iterate through the indices of the seen array (from 0 to max_value).\n",
"Collect the indices where the value remains False because these indices represent the numbers that were missing from the input list.\n",
"Return the Result:\n",
"\n",
"If you find any missing numbers, return the list of these numbers.\n",
"If no missing numbers are found (i.e., all indices are marked True), return -1.\n",
"Summary:\n",
"\n",
"Time Complexity: O(n), since you scan through the list and then through the boolean array.\n",
"Space Complexity: O(n), due to the extra boolean array."
]
},
{
Expand Down Expand Up @@ -338,9 +518,9 @@
],
"metadata": {
"kernelspec": {
"display_name": "Python 3",
"display_name": "Python (Pixi DSI)",
"language": "python",
"name": "python3"
"name": "pixi-dsi"
},
"language_info": {
"codemirror_mode": {
Expand All @@ -352,7 +532,7 @@
"name": "python",
"nbconvert_exporter": "python",
"pygments_lexer": "ipython3",
"version": "3.11.7"
"version": "3.7.12"
}
},
"nbformat": 4,
Expand Down
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