LeetCode Exercise 17：01 Matrix

题名：01矩阵，最近的0

难度：Medium

题目描述：





代码如下：

class Solution {
public:
vector<vector<int>> updateMatrix(vector<vector<int>>& A) {
int r = A.size(), c = A[0].size();
vector<vector<int>> ans(r, vector<int>(c));
queue<pair<int, int>> q;
int D[4][2] = {{-1, 0}, {1, 0}, {0, -1}, {0, 1}};

for(int i = 0; i < r; i++){
for(int j = 0; j < c; j++){
if(A[i][j] == 0){
ans[i][j] = 0;
q.push(make_pair(i, j));
}
else{
ans[i][j] = -1;
}
}
}

while(!q.empty()){
pair<int, int> p = q.front();
q.pop();
for(int i = 0; i < 4; i++){
int row = p.first + D[i][0];
int col = p.second + D[i][1];
if(row >= 0 && row < r && col >= 0 && col < c && ans[row][col] == -1){
ans[row][col] = ans[p.first][p.second] + 1;
q.push(make_pair(row, col));
}
}
}

return ans;
}
};