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Assignment 1 practice #90

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1ca9456
solve questions 1 and 2 for practice
jseis Jan 28, 2026
0375520
fix corner case in practice problem 2
jseis Feb 6, 2026
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62 changes: 54 additions & 8 deletions 02_activities/assignments/assignment_1.ipynb
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Original file line number Diff line number Diff line change
Expand Up @@ -67,15 +67,31 @@
},
{
"cell_type": "code",
"execution_count": null,
"execution_count": 46,
"metadata": {},
"outputs": [],
"source": [
"from typing import List\n",
"\n",
"def first_duplicate(nums: List[int]) -> int:\n",
" # TODO\n",
" pass"
" num_set = set()\n",
" for num in nums:\n",
" if num in num_set:\n",
" return num\n",
" else:\n",
" num_set.add(num)\n",
" return -1\n"
]
},
{
"cell_type": "code",
"execution_count": 47,
"metadata": {},
"outputs": [],
"source": [
"assert first_duplicate([3, 1, 4, 2, 5, 1, 6]) == 1\n",
"assert first_duplicate([7, 8, 9, 10]) == -1\n",
"assert first_duplicate([4, 5, 6, 4, 6]) == 4"
]
},
{
Expand Down Expand Up @@ -112,13 +128,40 @@
},
{
"cell_type": "code",
"execution_count": 1,
"execution_count": 67,
"metadata": {},
"outputs": [],
"source": [
"def bracket_matches(b1:str, b2:str):\n",
" if b1 == '(' and b2 == ')' or b1 == '[' and b2 == ']' or b1 == '{' and b2 == '}':\n",
" return True\n",
" else:\n",
" return False\n",
"\n",
"def is_valid_brackets(s: str) -> bool:\n",
" # TODO\n",
" pass"
" stack = []\n",
" for brack in s:\n",
" if brack == '(' or brack == '[' or brack == '{':\n",
" stack.append(brack)\n",
" elif stack:\n",
" opening_brack = stack.pop()\n",
" if not bracket_matches(opening_brack, brack):\n",
" return False\n",
" else:\n",
" return False\n",
" return len(stack) == 0\n"
]
},
{
"cell_type": "code",
"execution_count": 68,
"metadata": {},
"outputs": [],
"source": [
"assert is_valid_brackets(\"([]{})\") == True\n",
"assert is_valid_brackets(\"([)]\") == False\n",
"assert is_valid_brackets(\"()[]{}\") == True\n",
"assert is_valid_brackets(\"[{]}\") == False\n"
]
},
{
Expand Down Expand Up @@ -300,8 +343,11 @@
}
],
"metadata": {
"interpreter": {
"hash": "7ccc5368cda896b2ab91e5e6fe72ec210001cb3dc1ca1ba63746389bd9a7a2c9"
},
"kernelspec": {
"display_name": "Python 3 (ipykernel)",
"display_name": "Python 3.11.14 64-bit (system)",
"language": "python",
"name": "python3"
},
Expand All @@ -315,7 +361,7 @@
"name": "python",
"nbconvert_exporter": "python",
"pygments_lexer": "ipython3",
"version": "3.11.5"
"version": "3.11.14"
}
},
"nbformat": 4,
Expand Down