Create path-with-maximum-gold.py

Author: kamyu104

Python/path-with-maximum-gold.py

@@ -0,0 +1,29 @@
+# Time:  O(m^2 * n^2)
+# Space: O(m * n)
+
+class Solution(object):
+    def getMaximumGold(self, grid):
+        """
+        :type grid: List[List[int]]
+        :rtype: int
+        """
+        directions = [(0, 1), (1, 0), (0, -1), (-1, 0)]
+        def backtracking(grid, i, j):
+            result = 0
+            grid[i][j] *= -1
+            for dx, dy in directions:
+                ni, nj = i+dx, j+dy
+                if not (0 <= ni < len(grid) and
+                        0 <= nj < len(grid[0]) and
+                        grid[ni][nj] > 0):
+                    continue
+                result = max(result, backtracking(grid, ni, nj))
+            grid[i][j] *= -1
+            return grid[i][j] + result
+
+        result = 0
+        for i in xrange(len(grid)):
+            for j in xrange(len(grid[0])):
+                if grid[i][j]:
+                    result = max(result, backtracking(grid, i, j))
+        return result