BFS（宽度优先搜索）C++（Acwing）

代码：

#include <cstring>
#include <iostream>
#include <algorithm>using namespace std;typedef pair<int, int> PII;const int N = 110;int n, m;
int g[N][N];
int d[N][N];
PII q[N * N];int bfs()
{int hh = 0, tt = 0;q[0] = {0, 0};memset(d, -1, sizeof d);d[0][0] = 0;int dx[4] = {-1, 0, 1, 0}, dy[4] = {0, 1, 0, -1};while(hh <= tt){auto t = q[hh++];for(int i = 0; i < 4; i++){int x = t.first + dx[i], y = t.second + dy[i];if(x >= 0 && x < n && y >= 0 && y < m && g[x][y] == 0 && d[x][y] == -1){d[x][y] = d[t.first][t.second] + 1;q[++tt] = {x, y};}}}return d[n - 1][m - 1];
}int main()
{cin >> n >> m;for(int i = 0; i < n; i++)for(int j = 0; j < m; j++)cin >> g[i][j];cout << bfs() << endl;return 0;
}