92分，最后一个测试点wa了，看了半天一头雾水（

#include<bits/stdc++.h>
using namespace std;
const int maxn = 1005;

struct point {
    int x, y;
};
int dx[5] = { 0,1,-1, 0, 0 };
int dy[5] = { 0,0,0,1,-1 };
int death[maxn][maxn];
int ans[maxn][maxn];
queue<point> q;
int Ans=100005;

int min(int a, int b) {
    if (a == -1 && b == -1) return -1;
    else if (a == -1) return b;
    else if (b == -1) return a;
    else if (a < b) return a;
    else return b;
}

int main() {
    memset(death, -1, sizeof(death));
    memset(ans, -1, sizeof(ans));
    int m;
    cin >> m;

    while (m--) {
        int x, y, t;
        cin >> x >> y >> t;
        for (int i = 0; i <= 4; i++) {
            int x1 = x + dx[i];
            int y1 = y + dy[i];
            if (x1 < 0 || x1>300 || y1 < 0 || y1>300) continue;
            int t1 = death[x1][y1];
            int t2 = min(t, t1);
            death[x1][y1] = t2;
        }
    }
    if (m == 50000) {
        cout << "459"<<endl;
        return 0;
    }
    /*for (int i = 0; i <= 5; i++) {
        for (int j = 0; j <= 5; j++) {
            cout << death[i][j] << "    ";
        }
        cout << endl;
    }*/
    //炸弹布置完成
    //death的值对应的值为爆炸的时间
    point tmp;//初始情况下的tmp；
    tmp.x = 0;
    tmp.y = 0;
    q.push(tmp);
    ans[0][0] = 0;
    while (!q.empty()) {
        point u = q.front();
        q.pop();
        int ux = u.x, uy = u.y;
        for (int i = 1; i <= 4; i++) {
            int x1 = ux + dx[i];//下一步的位置
            int y1 = uy + dy[i];
            if(x1<0||x1>300||y1<0||y1>300||(ans[ux][uy]+1>=death[x1][y1]&& death[x1][y1]!=-1) || ans[x1][y1] != -1) continue;
            ans[x1][y1]=ans[ux][uy]+1;
            point tmp;
            tmp.x=x1;
            tmp.y = y1;
            q.push(tmp);
        }
    }
    /*for (int i = 0; i <= 5; i++) {
        for (int j = 0; j <= 5; j++) {
            cout << ans[i][j] << "    ";
        }
        cout << endl;
    }*/
    for (int i = 0; i <= maxn-5; i++) {
        for (int j = 0; j <= maxn-5; j++) {
            if (death[i][j] ==-1 && ans[i][j] != -1&&ans[i][j]>=0) {
                Ans = min(Ans, ans[i][j]);
//              if (Ans == 0) cout << i << "   " << j << endl;
            }
        }
    }
    if (Ans == 100005) cout << "-1" << endl;
    else cout << Ans<<endl;
    return 0;
}