submission

graphs/minimum_effort_path.py

@@ -15,4 +15,34 @@ def min_effort_path(heights):
         int
             minimum effort required to navigate the path from (0, 0) to heights[rows - 1][columns - 1]
     """
-    pass
+    if not heights:
+        return 0
+
+    m, n = len(heights), len(heights[0])
+    DIR = [0, 1, 0, -1, 0]
+
+    def dfs(r, c, visited, threadshold):
+        if r == m-1 and c == n-1: 
+            return True
+        visited[r][c] = True
+        for i in range(4):
+            nr, nc = r+DIR[i], c+DIR[i+1]
+            if nr < 0 or nr == m or nc < 0 or nc == n or visited[nr][nc]: continue
+            if abs(heights[nr][nc]-heights[r][c]) <= threadshold and dfs(nr, nc, visited, threadshold): 
+                return True
+        return False
+
+    def can_reach_destination(threadshold):
+        visited = [[False] * n for _ in range(m)]
+        return dfs(0, 0, visited, threadshold)
+
+    left = 0
+    result = right = 10**6
+    while left <= right:
+        mid = left + (right-left) // 2
+        if can_reach_destination(mid):
+            right = mid - 1
+            result = mid
+        else:
+            left = mid + 1
+    return result