20190125

Author: mJackie

TopInterview.md

@@ -46,6 +46,8 @@
 
 | 070  | [Climbing Stairs](https://leetcode.com/problems/climbing-stairs/) | Easy | [Java](./code/lc70.java)
 
+| 073  |
+
 | 075  | [Sort Colors](https://leetcode.com/problems/sort-colors/)|Medium| [Java](./code/lc75.java)
 | 076  | [Minimum Window Substring](https://leetcode.com/problems/minimum-window-substring) | Hard| [Java](./code/lc76.java)
 | 078  | [Subsets](https://leetcode.com/problems/subsets/) |Medium| [Java](./code/lc78.java)

code/lc73.java

@@ -0,0 +1,30 @@
+package code;
+/*
+ * 73. Set Matrix Zeroes
+ * 题意：把含有0的行和列都设成0
+ * 难度：Medium
+ * 分类：Array
+ * 思路：用第一行和第一列作为标志位。注意赋值的时候从后往前，防止标志位被改变
+ * Tips：注意赋值的顺序，防止标志位被改变
+ *       思路是很简单，但有许多细节
+ */
+public class lc73 {
+    public void setZeroes(int[][] matrix) {
+        boolean col0 = false;   //因为 matrix[0][0] 只有一个位置，所以用一个变量单独记录
+        for (int i = 0; i < matrix.length ; i++) {
+            if(matrix[i][0]==0) col0 = true;
+            for (int j = 1; j < matrix[0].length ; j++) {
+                if(matrix[i][j]==0){
+                    matrix[i][0] = 0;
+                    matrix[0][j] = 0;
+                }
+            }
+        }
+        for (int i = matrix.length-1; i >= 0 ; i--) {   //从后往前，标志位那一行最后改变
+            for (int j = matrix[0].length-1; j >= 1 ; j--) {    // j>=1 不包含j==0
+                if( matrix[i][0]==0 || matrix[0][j]==0 ) matrix[i][j] = 0;
+            }
+            if(col0==true) matrix[i][0]=0;  //要在for循环后，再把[i][0]改变
+        }
+    }
+}

readme.md

@@ -61,6 +61,7 @@ Language: Java
 | 069 [Java](./code/lc69.java)
 | 070 [Java](./code/lc70.java)
 | 072 [Java](./code/lc72.java)
+| 073 [Java](./code/lc73.java)
 | 075 [Java](./code/lc75.java)
 | 076 [Java](./code/lc76.java)
 | 078 [Java](./code/lc78.java)