为什么只有二十一分，已绝望

#include<bits/stdc++.h>
using namespace std;
#define maxn 310
struct coord{
    int x, y;
};
queue<coord > Q;
int ans[maxn][maxn], death[maxn][maxn];
int wk[4][2] = {{0, 1}, {1, 0}, {-1, 0}, {0, -1}};
int main(){
    int m, Ans = 100000;
    memset(ans, -1, sizeof(ans));
    memset(death, 0x7f, sizeof(death));
    cin >> m;
    for(int i = 1;i <= m;i++){
        int x, y, t;
        cin >> x >> y >> t;
#define MIN(x, y, t) if(x >= 0 && y >= 0) death[x][y] = min(death[x][y], t)
        MIN(x, y, t);
        for(int k = 0;k < 4;k++) MIN(x + wk[k][0], y + wk[k][1], t);
    }
    Q.push((coord){0, 0});
    ans[0][0] = 0;
    while(!Q.empty()){
        coord u = Q.front();
        int ux = u.x, uy = u.y;
        Q.pop();
        for(int k = 0;k < 4;k++){
            int x = ux + wk[k][0], y = uy + wk[k][1];
            if(x < 0 || y < 0 || ans[x][y] != -1 || ans[ux][uy] + 1 >= death[x][y]) continue;
            ans[x][y] = ans[ux][uy] + 1;
            Q.push((coord){x, y});
        }
    }
    for(int i = 0;i <= 305;i++){
        for(int j = 0;j <= 305;j++){
            if(death[i][j] > 1000 && ans[i][j] != -1)
                Ans = min(Ans, ans[i][j]);
        }
    }
    if(Ans == 100000) puts("-1");
    else printf("%d", Ans);

    return 0;
}