upd

algorithms/labs/lab8/code/search/1.py

@@ -0,0 +1,38 @@
+def exist(board, word):
+    rows, cols = len(board), len(board[0])
+    visited = set()
+
+    def dfs(r, c, k):
+        if k == len(word):
+            return True
+        if (
+            r < 0
+            or r >= rows
+            or c < 0
+            or c >= cols
+            or (r, c) in visited
+            or board[r][c] != word[k]
+        ):
+            return False
+        visited.add((r, c))
+        ok = (
+            dfs(r + 1, c, k + 1)
+            or dfs(r - 1, c, k + 1)
+            or dfs(r, c + 1, k + 1)
+            or dfs(r, c - 1, k + 1)
+        )
+        visited.remove((r, c))
+        return ok
+
+    for r in range(rows):
+        for c in range(cols):
+            if dfs(r, c, 0):
+                return True
+    return False
+
+
+if __name__ == "__main__":
+    board = [["A", "B", "C", "E"], ["S", "F", "C", "S"], ["A", "D", "E", "E"]]
+    print(exist(board, "ABCCED"))
+    print(exist(board, "SEE"))
+    print(exist(board, "ABCB"))

algorithms/labs/lab8/code/search/2.py

@@ -0,0 +1,22 @@
+def search_rotated(nums, target):
+    l, r = 0, len(nums) - 1
+    while l <= r:
+        m = (l + r) // 2
+        if nums[m] == target:
+            return m
+        if nums[m] >= nums[l]:
+            if nums[l] <= target < nums[m]:
+                r = m - 1
+            else:
+                l = m + 1
+        else:
+            if nums[m] < target <= nums[r]:
+                l = m + 1
+            else:
+                r = m - 1
+    return -1
+
+
+if __name__ == "__main__":
+    print(search_rotated([4, 5, 6, 7, 0, 1, 2], 0))
+    print(search_rotated([4, 5, 6, 7, 0, 1, 2], 3))

algorithms/labs/lab8/code/search/3.py

@@ -0,0 +1,31 @@
+def search_matrix(matrix, target):
+    if not matrix or not matrix[0]:
+        return False
+    top, bot = 0, len(matrix) - 1
+    while top <= bot:
+        mid = (top + bot) // 2
+        if matrix[mid][0] <= target <= matrix[mid][-1]:
+            row = mid
+            break
+        if target < matrix[mid][0]:
+            bot = mid - 1
+        else:
+            top = mid + 1
+    else:
+        return False
+    l, r = 0, len(matrix[row]) - 1
+    while l <= r:
+        m = (l + r) // 2
+        if matrix[row][m] == target:
+            return True
+        if matrix[row][m] < target:
+            l = m + 1
+        else:
+            r = m - 1
+    return False
+
+
+if __name__ == "__main__":
+    matrix = [[1, 3, 5, 7], [10, 11, 16, 20], [23, 30, 34, 60]]
+    print(search_matrix(matrix, 3))
+    print(search_matrix(matrix, 13))