otters - c17 diana m.

graphs/minimum_effort_path.py

@@ -1,3 +1,5 @@
+import heapq
+
 def min_effort_path(heights):
     """ Given a 2D array of heights, write a function to return
         the path with minimum effort.
@@ -15,4 +17,35 @@ 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
+
+    seen = set()
+
+    n_rows = len(heights)
+    n_cols = len(heights[0])
+
+    min_effort = 0
+    pq = [(0,0,0)]
+
+    directions = [(0,1), (0,-1), (1,0), (-1,0)]
+
+    while pq != []:
+
+        effort, row, col = heapq.heappop(pq)
+        seen.add((row, col))
+        min_effort = max(min_effort, effort)
+
+        final= row == n_rows-1 and col == n_cols-1
+        if final: 
+            return min_effort
+
+        for x, y in directions:
+            new_row = row + x
+            new_col = col + y
+            if n_rows > new_row >= 0 <= new_col < n_cols and (new_row, new_col) not in seen:
+                effort = abs(heights[row][col] - heights[new_row][new_col])
+                heapq.heappush(pq, (effort, new_row, new_col))
+
+    return min_effort
+