Created
April 1, 2015 19:45
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1.7
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public class Solution{ | |
public void setZeroes(int[][] matrix){ | |
if(matrix == null || matrix.length ==0||matrix[0].length == 0) | |
return; | |
boolean rowHasZero = false; | |
boolean colHasZero = false; | |
//如果行列里面有0的话,记录一个为0就好,反正都是要变为0的,就先跳出,待程序最后再进行置0的操作,因为第一行和第一列是要被用来作为 | |
//判断行和判断列的 | |
for(int i = 0; i< matrix.length; i++) | |
{ | |
if(matrix[i][0] == 0) | |
{ | |
colHasZero = true; | |
break; | |
} | |
} | |
for(int j = 0;j<matrix[0].length;j++) | |
{ | |
if(matrix[0][j] == 0) | |
{ | |
rowHasZero = true; | |
break; | |
} | |
} | |
//因为将第一行和第一列作为判断行列了,原来矩阵减少了,所以i和j要从1来开始递增判断 | |
for(int i =1;i<matrix.length;i++){ | |
for(int j = 1;j< matrix[0].length;j++){ | |
if(matrix[i][j] == 0) | |
{ | |
matrix[i][0] =0; | |
matrix[0][j] =0; | |
} | |
} | |
} | |
//对上一个判断的执行,如果行列存在有0,那么就将这一行与这一列全部置为0 | |
for(int i = 1;i<matrix.length;i++){ | |
for(int j=1;j<matrix[0].length;j++){ | |
if(matrix[i][0] == 0||matrix[0][j] ==0) | |
matrix[i][j] =0; | |
} | |
} | |
//如果在题目之前开始判断的这一列存在有0的话,那么col为true,那么就可以将这一列所有全部置为0 | |
if(colHasZero) | |
{ | |
for(int i =0;i<matrix.length;i++) | |
matrix[i][0] =0; | |
} | |
//如果在题目之前开始判断的这一行存在有一个0的话,那么就不需要继续判断了,反正都是要变成0的。如果为true的话,那么就将 | |
//这一行的所有元素也都变成0 | |
if(rowHasZero) | |
{ | |
for(int i =0;i<matrix[0].length;i++) | |
matrix[0][i] = 0; | |
} | |
} | |
} |
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