adding algo

src/my_project/interviews/top_150_questions_round_22/ex_33_minimum_window_substring.py

@@ -0,0 +1,51 @@
+from typing import List, Union, Collection, Mapping, Optional
+from abc import ABC, abstractmethod
+from collections import Counter
+
+class Solution:
+    def minWindow(self, s: str, t: str) -> str:
+        if not s or not t or len(s) < len(t):
+            return ""
+
+        # Frequency map of characters needed from t
+        t_freq = Counter(t)
+        required = len(t_freq)  # Number of unique characters in t
+
+        # Window character frequencies
+        window_freq = {}
+
+        # Track how many unique characters in window have desired frequency
+        formed = 0
+
+        # Left and right pointers
+        left = 0
+        min_len = float('inf')
+        min_left = 0
+
+        for right in range(len(s)):
+            # Add character from right to window
+            char = s[right]
+            window_freq[char] = window_freq.get(char, 0) + 1
+
+            # Check if frequency of current character matches desired frequency
+            if char in t_freq and window_freq[char] == t_freq[char]:
+                formed += 1
+
+            # Try to contract window until it's no longer valid
+            while left <= right and formed == required:
+                # Update result if current window is smaller
+                if right - left + 1 < min_len:
+                    min_len = right - left + 1
+                    min_left = left
+
+                # Remove leftmost character from window
+                left_char = s[left]
+                window_freq[left_char] -= 1
+
+                # Check if window is no longer valid
+                if left_char in t_freq and window_freq[left_char] < t_freq[left_char]:
+                    formed -= 1
+
+                left += 1
+
+        return "" if min_len == float('inf') else s[min_left:min_left + min_len]

src/my_project/interviews/top_150_questions_round_22/ex_34_valid_sudoku.py

@@ -0,0 +1,32 @@
+from typing import List, Union, Collection, Mapping, Optional
+from abc import ABC, abstractmethod
+
+class Solution:
+    def isValidSudoku(self, board: List[List[str]]):
+        return (self.is_row_valid(board) and
+                self.is_col_valid(board) and
+                self.is_square_valid(board))
+
+    def is_row_valid(self, board: List[List[str]]):
+        for row in board:
+            if not self.is_unit_valid(row):
+                return False
+        return True
+
+    def is_col_valid(self, board: List[List[str]]):
+        for col in zip(*board):
+            if not self.is_unit_valid(col):
+                return False
+        return True
+
+    def is_square_valid(self, board: List[List[str]]):
+        for i in (0, 3, 6):
+            for j in (0, 3, 6):
+                square = [board[x][y] for x in range(i, i + 3) for y in range(j, j + 3)]
+                if not self.is_unit_valid(square):
+                    return False
+        return True
+
+    def is_unit_valid(self, unit):
+        unit = [i for i in unit if i != '.']
+        return len(set(unit)) == len(unit)

tests/test_150_questions_round_22/test_33_minimum_window_substring_round_22.py

@@ -0,0 +1,23 @@
+import unittest
+from src.my_project.interviews.top_150_questions_round_22\
+.ex_33_minimum_window_substring import Solution
+
+class MinimumWindowSubstringTestCase(unittest.TestCase):
+
+    def test_first_pattern(self):
+        solution = Solution()
+        output = solution.minWindow(s = "ADOBECODEBANC", t = "ABC")
+        target = "BANC"
+        self.assertEqual(output, target)
+
+    def test_second_pattern(self):
+        solution = Solution()
+        output = solution.minWindow(s = "a", t = "a")
+        target = "a"
+        self.assertEqual(output, target)
+
+    def test_third_pattern(self):
+        solution = Solution()
+        output = solution.minWindow(s = "a", t = "aa")
+        target = ""
+        self.assertEqual(output, target)        

tests/test_150_questions_round_22/test_34_valid_sudoku_round_22.py

@@ -0,0 +1,33 @@
+import unittest
+from src.my_project.interviews.top_150_questions_round_22\
+.ex_34_valid_sudoku import Solution
+
+class ValidSudokuTestCase(unittest.TestCase):
+
+    def test_first_pattern(self):
+        solution = Solution()
+        output = solution.isValidSudoku(board = 
+[["5","3",".",".","7",".",".",".","."]
+,["6",".",".","1","9","5",".",".","."]
+,[".","9","8",".",".",".",".","6","."]
+,["8",".",".",".","6",".",".",".","3"]
+,["4",".",".","8",".","3",".",".","1"]
+,["7",".",".",".","2",".",".",".","6"]
+,[".","6",".",".",".",".","2","8","."]
+,[".",".",".","4","1","9",".",".","5"]
+,[".",".",".",".","8",".",".","7","9"]])        
+        self.assertTrue(output)
+
+    def test_second_pattern(self):
+        solution = Solution()
+        output = solution.isValidSudoku(board = 
+[["8","3",".",".","7",".",".",".","."]
+,["6",".",".","1","9","5",".",".","."]
+,[".","9","8",".",".",".",".","6","."]
+,["8",".",".",".","6",".",".",".","3"]
+,["4",".",".","8",".","3",".",".","1"]
+,["7",".",".",".","2",".",".",".","6"]
+,[".","6",".",".",".",".","2","8","."]
+,[".",".",".","4","1","9",".",".","5"]
+,[".",".",".",".","8",".",".","7","9"]])
+        self.assertFalse(output)