Add problem 778 - Swim In Rising Water

Author: anirudhology

problems/graph/swim_in_rising_water.py

@@ -0,0 +1,31 @@
+import heapq
+from typing import List
+
+
+class SwimInRisingWater:
+    @staticmethod
+    def swimInWater(grid: List[List[int]]) -> int:
+        # Dimensions of the grid
+        n = len(grid)
+        # Min heap to store the cells based on the lowest value
+        min_heap = [(grid[0][0], 0, 0)]
+        # Array to mark the visited cells
+        visited = [[False] * n for _ in range(n)]
+        visited[0][0] = True
+        # Directions
+        directions = [[0, 1], [1, 0], [0, -1], [-1, 0]]
+        # Loop until heap is empty
+        while min_heap:
+            time, i, j = heapq.heappop(min_heap)
+            # Check if we have reached the last cell
+            if i == n - 1 and j == n - 1:
+                return time
+            # Move in all four directions
+            for direction in directions:
+                x, y = i + direction[0], j + direction[1]
+                # Check for out of bounds
+                if x < 0 or x >= n or y < 0 or y >= n or visited[x][y]:
+                    continue
+                visited[x][y] = True
+                heapq.heappush(min_heap, (max(grid[x][y], time), x, y))
+        return -1

tests/graph/swim_in_rising_water_test.py

@@ -0,0 +1,42 @@
+import unittest
+
+from problems.graph.swim_in_rising_water import SwimInRisingWater
+
+
+class TestSwimInRisingWater(unittest.TestCase):
+    def test_swim_in_water(self):
+        swim_in_rising_water = SwimInRisingWater()
+
+        # Test case 1
+        grid1 = [[0, 2], [1, 3]]
+        expected1 = 3
+        self.assertEqual(swim_in_rising_water.swimInWater(grid1), expected1)
+
+        # Test case 2
+        grid2 = [
+            [0, 1, 2, 3, 4],
+            [24, 23, 22, 21, 5],
+            [12, 13, 14, 15, 16],
+            [11, 17, 18, 19, 20],
+            [10, 9, 8, 7, 6]
+        ]
+        expected2 = 16
+        self.assertEqual(swim_in_rising_water.swimInWater(grid2), expected2)
+
+        # Edge case: single cell
+        grid3 = [[0]]
+        expected3 = 0
+        self.assertEqual(swim_in_rising_water.swimInWater(grid3), expected3)
+
+        # Edge case: larger grid
+        grid4 = [
+            [0, 1, 2],
+            [3, 4, 5],
+            [6, 7, 8]
+        ]
+        expected4 = 8
+        self.assertEqual(swim_in_rising_water.swimInWater(grid4), expected4)
+
+
+if __name__ == "__main__":
+    unittest.main()