solve 73.set-matrix-zeroes

Author: andavid

vscode/73.set-matrix-zeroes.java

@@ -0,0 +1,103 @@
+/*
+ * @lc app=leetcode id=73 lang=java
+ *
+ * [73] Set Matrix Zeroes
+ *
+ * https://leetcode.com/problems/set-matrix-zeroes/description/
+ *
+ * algorithms
+ * Medium (40.62%)
+ * Likes:    1243
+ * Dislikes: 219
+ * Total Accepted:    231.3K
+ * Total Submissions: 568.7K
+ * Testcase Example:  '[[1,1,1],[1,0,1],[1,1,1]]'
+ *
+ * Given a m x n matrix, if an element is 0, set its entire row and column to
+ * 0. Do it in-place.
+ *
+ * Example 1:
+ *
+ *
+ * Input:
+ * [
+ * [1,1,1],
+ * [1,0,1],
+ * [1,1,1]
+ * ]
+ * Output:
+ * [
+ * [1,0,1],
+ * [0,0,0],
+ * [1,0,1]
+ * ]
+ *
+ *
+ * Example 2:
+ *
+ *
+ * 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?
+ *
+ *
+ */
+class Solution {
+  public void setZeroes(int[][] matrix) {
+    boolean isFirstCol = false;
+    int row = matrix.length;
+    int col = matrix[0].length;
+
+    for (int i = 0; i < row; i++) {
+      if (matrix[i][0] == 0) {
+        isFirstCol = true;
+      }
+
+      for (int j = 1; j < col; j++) {
+        if (matrix[i][j] == 0) {
+          matrix[i][0] = 0;
+          matrix[0][j] = 0;
+        }
+      }
+    }
+
+    for (int i = 1; i < row; i++) {
+      for (int j = 1; j < col; j++) {
+        if (matrix[i][0] == 0 || matrix[0][j] == 0) {
+          matrix[i][j] = 0;
+        }
+      }
+    }
+
+    if (matrix[0][0] == 0) {
+      for (int j = 0; j < col; j++) {
+        matrix[0][j] = 0;
+      }
+    }
+
+    if (isFirstCol) {
+      for (int i = 0; i < row; i++) {
+        matrix[i][0] = 0;
+      }
+    }
+  }
+}
+