题解

#include <bits/stdc++.h>
using namespace std;
int n, m, dp[2005][2005], sx, sy, ex, ey;
char mp[2005][2005];
bool vis[2005][2005], f;
int dx[4] = {-1, 1, 0, 0};
int dy[4] = {0, 0, -1, 1};

bool inmp(int x, int y) {return x >= 1 && x <= n && y >= 1 && y <= m;}

int main() {
    cin >> n >> m;
    for (int i = 1;i <= n;i++) {
        for (int j = 1;j <= m;j++) {
            cin >> mp[i][j];
            if (mp[i][j] == '@') sx = i, sy = j;
            if (mp[i][j] == '*') ex = i,ey = j;
        }
    }
    queue<pair<int, int>> q;
    q.push({sx, sy});
    while (!q.empty()) {
        int x = q.front().first;
        int y = q.front().second;
        q.pop();
        if (x == ex && y == ey) {
            f = 1;
            break;
        }
        vis[x][y] = 1;
        for (int k = 0;k < 4;k++) {
            int nx = x + dx[k];
            int ny = y + dy[k];
            if (!inmp(nx, ny) || vis[nx][ny] || mp[nx][ny] == '#') continue;
            vis[nx][ny] = 1;
            dp[nx][ny] = dp[x][y] + 1;
            q.push({nx, ny});
        }
    }
    cout << (f ? dp[ex][ey] : -1);
}