题目链接:https://leetcode-cn.com/problems/rotting-oranges/
一分钟写完系列,可以直接把二维坐标一维化
代码如下:
class Solution {
public:
bool inmap(int xx, int yy, int n, int m) {
return xx >= 0 && xx < n && yy >= 0 && yy < m;
}
int orangesRotting(vector<vector<int>>& grid) {
int res = 0;
int n = grid.size();
if(n == 0) {
return 0;
}
int m = grid[0].size();
queue<int> q;
for(int i = 0; i < n; i++) {
for(int j = 0; j < m; j++) {
if(grid[i][j] == 2) {
q.push(i * m + j);
}
}
}
int dx[4] = {-1, 0, 1, 0};
int dy[4] = {0, -1, 0, 1};
while(!q.empty()) {
int len = q.size();
while(len--) {
int now = q.front();
q.pop();
int x = now / m;
int y = now % m;
for(int i = 0; i < 4; i++) {
int xx = x + dx[i], yy = y + dy[i];
if(inmap(xx, yy, n, m) && grid[xx][yy] == 1) {
grid[xx][yy] = 0;
q.push(xx * m + yy);
// printf("xx = %d, yy = %d\n", xx, yy);
}
}
}
res++;
}
for(int i = 0; i < n; i++) {
for(int j = 0; j < m; j++) {
if(grid[i][j] == 1) {
return -1;
}
}
}
return max(0, res - 1);
}
};