73. Set Matrix Zeroes

Diffculty: Medium
159 / 159 test cases passed.
Runtime: 128 ms
Memory Usage: 14.2 MB

Author: YuriSpiridonov

Medium/73.SetMatrixZeroes.py

@@ -0,0 +1,50 @@
+"""
+    Given a m x n matrix, if an element is 0, set its entire row and column 
+    to 0. Do it in-place.
+
+    Example:
+    Input: 
+    [
+      [0,1,2,0],
+      [3,4,5,2],
+      [1,3,1,5]
+    ]
+    Output: 
+    [
+      [0,0,0,0],
+      [0,4,5,0],
+      [0,3,1,0]
+    ]
+    Follow up:
+        - A straight forward solution using O(mn) space is probably a bad idea.
+        - A simple improvement uses O(m + n) space, but still not the best 
+          solution.
+        - Could you devise a constant space solution?
+"""
+#Diffculty: Medium
+#159 / 159 test cases passed.
+#Runtime: 128 ms
+#Memory Usage: 14.2 MB
+
+#Runtime: 128 ms, faster than 98.17% of Python3 online submissions for Set Matrix Zeroes.
+#Memory Usage: 14.2 MB, less than 66.80% of Python3 online submissions for Set Matrix Zeroes.
+
+class Solution:
+    def setZeroes(self, matrix: List[List[int]]) -> None:
+        """
+        Do not return anything, modify matrix in-place instead.
+        """
+        row_size = len(matrix[0])
+        col_size = len(matrix)
+        rows_to_zero = set()
+        cols_to_zero = set()
+        for i in range(col_size):
+            for j in range(row_size):
+                if matrix[i][j] == 0:
+                    rows_to_zero.add(i)
+                    cols_to_zero.add(j)
+        for i in range(col_size):
+            if i in rows_to_zero:
+                matrix[i] = [0] * row_size
+            for j in cols_to_zero:
+                matrix[i][j] = 0