求助大佬，不知道为什么最后五个点RE

#include <bits/stdc++.h>
using namespace std;

const int N = 700;
struct node {
    int x, y, step;
};

int dirX[5] = {0,0,0,1,-1}, dirY[5] = {0,1,-1,0,0};
int drop[N][N];
int v[N][N];
queue<node> q;
int cnt;

int main() {
    int n; cin >> n;
    memset(drop,-1,sizeof(drop));
    for(int i = 0; i < n; i++){
        int x, y, t; cin >> x >> y >> t;
        for(int j = 0; j < 5; j++){
            int xx = x + dirX[j]; int yy = y + dirY[j];
            if(xx < 0 || yy < 0) continue;
            if(drop[xx][yy]==-1 || drop[xx][yy] > t) drop[xx][yy] = t; 
        }
    }
    for(int i = 0; i < n; i++){
        for(int j = 0; j < n; j++){
            if(drop[i][j]==-1) drop[i][j] = 99999; 
        }
    }

    q.push((node){0,0,0});
    v[0][0] = 1;
    while(!q.empty()){
        node temp = q.front();
        cnt = temp.step;
        q.pop();

        if(drop[temp.x][temp.y] == 99999){
            cout << cnt << endl;
            return 0;
        }

        for(int i = 1; i < 5; i++){
            int xx = temp.x + dirX[i]; int yy = temp.y + dirY[i];
            if(xx < 0 || yy < 0 || v[xx][yy]) continue;
            if(drop[xx][yy] <= cnt+1) continue;
            v[xx][yy] = 1;
            q.push((node){xx,yy,cnt+1});
        }
    }
    cout << -1 << endl;
    return 0;
}