Create stamping-the-grid.py

Python/stamping-the-grid.py

@@ -0,0 +1,29 @@
+# Time:  O(m * n)
+# Space: O(m * n)
+
+class Solution(object):
+    def possibleToStamp(self, grid, stampHeight, stampWidth):
+        """
+        :type grid: List[List[int]]
+        :type stampHeight: int
+        :type stampWidth: int
+        :rtype: bool
+        """
+        prefix = [[0]*(len(grid[0])+1) for _ in xrange(len(grid)+1)]
+        fit = [[0]*len(grid[0]) for _ in xrange(len(grid))]
+        for i in xrange(len(grid)):
+            for j in xrange(len(grid[0])):
+                prefix[i+1][j+1] = prefix[i+1][j]+prefix[i][j+1]-prefix[i][j]+(1^grid[i][j])
+                if i+1 >= stampHeight and j+1 >= stampWidth:
+                    x, y = i+1-stampHeight, j+1-stampWidth
+                    fit[i][j] = int(prefix[i+1][j+1]-prefix[x][j+1]-prefix[i+1][y]+prefix[x][y] == stampWidth*stampHeight)
+        prefix2 = [[0]*(len(grid[0])+1) for _ in xrange(len(grid)+1)]
+        for i in xrange(len(grid)):
+            for j in xrange(len(grid[0])):
+                prefix2[i+1][j+1] = prefix2[i+1][j]+prefix2[i][j+1]-prefix2[i][j]+fit[i][j]
+        for i in xrange(len(grid)):
+            for j in xrange(len(grid[0])):
+                x, y = min(i+stampHeight, len(grid)), min(j+stampWidth, len(grid[0]))
+                if not grid[i][j] and not prefix2[x][y]-prefix2[i][y]-prefix2[x][j]+prefix2[i][j]:
+                    return False
+        return True