题目：
Given a m x n matrix, if an element is 0, set its entire row and column to 0. Do it in place.
Did you use extra space?
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?
解答：
题意就是说，矩阵中每个零元素，它所在的行列全部置为 0。可能有多个 0 元素。
class Solution {
public:
void setZeroes(vector<vector<int>>& matrix) {
int row = matrix.size();
int col = matrix[0].size();
if(row <= 1 && col <= 1) return;
bool zerorow = false;
bool zerocol = false;
for(int i = 0; i < row; i++)
{
if(matrix[i][0] == 0)
{
zerocol = true;
break;
}
}
for(int i = 0; i < col; i++)
{
if(matrix[0][i] == 0)
{
zerorow = true;
break;
}
}
for(int i = 1; i < row; i++)
{
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++)
{
if(matrix[i][0] == 0)
{
for(int j = 1; j < col; j++) matrix[i][j] = 0;
}
}
for(int i = 1; i < col; i++)
{
if(matrix[0][i] == 0)
{
for(int j = 1; j < row; j++) matrix[j][i] = 0;
}
}
if(zerorow)
{
for(int i = 0; i< col; i++) matrix[0][i] = 0;
}
if(zerocol)
{
for(int i = 0; i< row; i++) matrix[i][0] = 0;
}
return;
}
};版权声明：本文为博主原创文章，转载请联系我的新浪微博 @iamironyoung
【LeetCode从零单刷】Set Matrix Zeroes
原文：http://blog.csdn.net/ironyoung/article/details/49556051