Create increment-submatrices-by-one.py

Author: kamyu104

Python/increment-submatrices-by-one.py

@@ -0,0 +1,27 @@
+# Time:  O(q + n^2)
+# Space: O(1)
+
+# line sweep, difference matrix (2d difference array)
+class Solution(object):
+    def rangeAddQueries(self, n, queries):
+        """
+        :type n: int
+        :type queries: List[List[int]]
+        :rtype: List[List[int]]
+        """
+        result = [[0]*n for _ in xrange(n)]
+        for r1, c1, r2, c2 in queries:
+            result[r1][c1] += 1
+            if c2+1 < len(result[0]):
+                result[r1][c2+1] -= 1
+            if r2+1 < len(result):
+                result[r2+1][c1] -= 1
+            if r2+1 < len(result) and c2+1 < len(result[0]):
+                result[r2+1][c2+1] += 1
+        for r in xrange(len(result)):
+            for c in xrange(len(result[0])-1):
+                result[r][c+1] += result[r][c]
+        for r in xrange(len(result)-1):
+            for c in xrange(len(result[0])):
+                result[r+1][c] += result[r][c]
+        return result