利用第一行和第一列存储状态:
- 首先记录第一行第一列中是否含有0
- 遍历矩阵,如果元素为0,将对应的行头和列头的元素置0
- 再次遍历矩阵,如果对应的行头或列头元素为0,将当前元素置0
- 最后,如果第一行原来就有0,将第一行置0,第一列同样操作
// // Created by jt on 2020/9/25. // #include <vector> using namespace std; class Solution { public: void setZeroes(vector<vector<int> > &matrix) { bool firstRowHas0 = false, firstColHas0 = false; for (int i = 0; i < matrix.size(); ++i) { if (matrix[i][0] == 0) { firstColHas0 = true; break; } } for (int i = 0; i < matrix[0].size(); ++i) { if (matrix[0][i] == 0) { firstRowHas0 = true; break; } } for (int i = 0; i < matrix.size(); ++i) { for (int j = 0; j < matrix[0].size(); ++j) { if (matrix[i][j] == 0) { matrix[0][j] = 0; matrix[i][0] = 0; } } } for (int i = 1; i < matrix.size(); ++i) { for (int j = 1; j < matrix[0].size(); ++j){ if (matrix[0][j] == 0 || matrix[i][0] == 0) matrix[i][j] = 0; } } if (firstRowHas0) { for (int i = 0; i < matrix[0].size(); ++i) { matrix[0][i] = 0; } } if (firstColHas0) { for (int i = 0; i < matrix.size(); ++i) { matrix[i][0] = 0; } } } };