Set Matrix Zeroes
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Given a m x n matrix, if an element is 0, set its entire row and column to 0. Do it in place.
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题意：给定矩阵，如果矩阵的某个位置为0，则把那一行那一列的所有元素都置为0
思路：用两个bool数组，分别记录应该把所有元素置为0的行和列
复杂度：时间O(m*n)，空间O(m+n)
void setZeroes(vector
> &matrix){
if(matrix.empty()) return ;
int rows = matrix.size(), columns = matrix[0].size();
vector
row(rows, false); vector
column(columns, false); for(int i = 0; i < rows; ++i){ for(int j = 0; j < columns; ++j){ if(matrix[i][j] == 0){ row[i] = column[j] = true; continue; } } } for(int i = 0; i < rows; ++i){ if(!row[i]) continue; for(int j = 0; j < columns; ++j){ matrix[i][j] = 0; } } for(int j = 0; j < columns; ++j){ if(!column[j]) continue; for(int i = 0; i < rows; ++i){ matrix[i][j] = 0; } } }