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prac: valid parentheses mapping solution reasoning #118

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22 changes: 10 additions & 12 deletions ...Code/easy/best_time_buy_sell_stock_121.py → ...Code/dump/best_time_buy_sell_stock_121.py
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Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,7 @@

class Solution:
"""

price = [7,6,4,3,1]
price = [7,1,5,3,6,4]
price_3 = [2,7,1,5,4]
Expand All @@ -30,7 +30,7 @@ class Solution:
update()
if min_price > price then min_price = price
if price - min_price > best_profit best_profit = min_price - price
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⚠️ Potential issue | 🟡 Minor

Docstring typo: profit update formula is inverted

The thought process says best_profit = min_price - price, but the correct formula is price - min_price (as correctly implemented at Line 74).

📝 Fix 
-        if price - min_price > best_profit best_profit = min_price - price
+        if price - min_price > best_profit: best_profit = price - min_price
🤖 Prompt for AI Agents 
Verify each finding against the current code and only fix it if needed.

In `@LeetCode/dump/best_time_buy_sell_stock_121.py` at line 32, The profit update
assigns the inverted expression; in the loop that compares price, min_price, and
best_profit (variables price, min_price, best_profit inside the solution
function, e.g., maxProfit), change the assignment so best_profit is set to price
- min_price (not min_price - price) when if price - min_price > best_profit;
ensure the conditional and assignment are properly separated/terminated so the
check updates best_profit correctly.


update
Day 0: price is 7 and min_price is 7 best_profit is 0
update
Expand All @@ -51,33 +51,31 @@ class Solution:
Boom! At the end, we return that

"""

def bruteForceMaxProfit(self, prices: List[int]) -> int:
best_profit = 0
for i in range(len(prices)):
for j in range(i + 1, len(prices)):
profit = prices[j] - prices[i]

best_profit = max(best_profit, profit)

return best_profit

def maxProfit(self, prices: List[int]) -> int:
min_price = float('inf')
min_price = float("inf")
best_profit = 0

for price in prices:
if price < min_price:
min_price = price

if price - min_price > best_profit:
best_profit = price - min_price

return best_profit





price_3 = [7,6,4,3,1]
price_3 = [7, 6, 4, 3, 1]
sol = Solution().maxProfit(price_3)
print(f"Best profit: {sol}")
print(f"Best profit: {sol}")
Comment on lines +79 to +81
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⚠️ Potential issue | 🟠 Major

Module-level side effects execute on import, polluting test output

Solution().maxProfit(price_3) and print(...) run unconditionally at module scope. Now that test_leetcode_easy.py (Line 88) imports from LeetCode.dump.best_time_buy_sell_stock_121 import Solution, every test run will execute this computation and emit stdout, dirtying pytest output.

Guard behind __main__:

-price_3 = [7, 6, 4, 3, 1]
-sol = Solution().maxProfit(price_3)
-print(f"Best profit: {sol}")
+if __name__ == "__main__":
+    price_3 = [7, 6, 4, 3, 1]
+    sol = Solution().maxProfit(price_3)
+    print(f"Best profit: {sol}")
📝 Committable suggestion

‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change
price_3 = [7, 6, 4, 3, 1]
sol = Solution().maxProfit(price_3)
print(f"Best profit: {sol}")
\ No newline at end of file
print(f"Best profit: {sol}")
if __name__ == "__main__":
price_3 = [7, 6, 4, 3, 1]
sol = Solution().maxProfit(price_3)
print(f"Best profit: {sol}")
🤖 Prompt for AI Agents 
Verify each finding against the current code and only fix it if needed.

In `@LeetCode/dump/best_time_buy_sell_stock_121.py` around lines 79 - 81, The
module currently runs Solution().maxProfit(price_3) and prints the result at
import time, causing side effects when tests import Solution; move those example
invocation lines (the price_3 assignment, the call to Solution().maxProfit, and
the print) into a guard block so they only run when executed as a script: wrap
them in if __name__ == "__main__": or remove them entirely so importing the
Solution class and its maxProfit method has no stdout or computation side
effects.

12 changes: 12 additions & 0 deletions LeetCode/easy/valid_parentheses_20.py
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Original file line number Diff line number Diff line change
@@ -0,0 +1,12 @@
class Solution:
def isValidByMapping(self, s: str) -> bool:
stack = []
mapping = {"}": "{", ")": "(", "]": "["}

for p in s:
if stack and p in mapping and stack[-1] == mapping[p]:
stack.pop()
else:
stack.append(p)

return len(stack) == 0
23 changes: 0 additions & 23 deletions tests/test_leetcode.py
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Original file line number Diff line number Diff line change
Expand Up @@ -248,29 +248,6 @@ def test_reverse_integer(x: int, expected: int):
assert result == expected


@pytest.mark.parametrize(
"s, expected",
[
("()", True), # Single pair
("()[]{}", True), # Multiple valid pairs
("(]", False), # Mismatched parentheses
("([)]", False), # Nested but invalid
("{[]}", True), # Properly nested
("", True), # Empty string
("(", False), # Single opening parenthesis
(")", False), # Single closing parenthesis
("(((((((((())))))))))", True), # Deeply nested
("(((((((((()))", False), # Deeply nested but incomplete
],
)
def test_is_valid_parentheses(s: str, expected: bool):
from LeetCode.valid_parentheses_20 import Solution

solution = Solution()
result = solution.isValid(s)
assert result == expected


@pytest.mark.parametrize(
"s, expected",
[
Expand Down
30 changes: 29 additions & 1 deletion tests/test_leetcode_easy.py
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Original file line number Diff line number Diff line change
Expand Up @@ -85,7 +85,7 @@ def test_generate(numRows, expected):
],
)
def test_max_profit(prices, expected):
from LeetCode.easy.best_time_buy_sell_stock_121 import Solution
from LeetCode.dump.best_time_buy_sell_stock_121 import Solution

solution = Solution()
assert solution.maxProfit(prices) == expected
Expand Down Expand Up @@ -182,3 +182,31 @@ def test_missing_number(nums, expected):

solution = Solution()
assert solution.missingNumber(nums) == expected


@pytest.mark.parametrize(
"s, expected",
[
("()", True), # Single pair
("()[]{}", True), # Multiple valid pairs
("(]", False), # Mismatched parentheses
("([)]", False), # Nested but invalid
("{[]}", True), # Properly nested
("", True), # Empty string
("(", False), # Single opening parenthesis
(")", False), # Single closing parenthesis
("(((((((((())))))))))", True), # Deeply nested
("(((((((((()))", False), # Deeply nested but incomplete
],
)
def test_is_valid_parentheses(s: str, expected: bool):
from LeetCode.easy.valid_parentheses_20 import Solution as Sol
from LeetCode.valid_parentheses_20 import Solution

solution = Solution()
result = solution.isValid(s)
assert result == expected

sol = Sol()
res = sol.isValidByMapping(s)
assert res == expected
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