第 14 测试点 $WA$ ，快要调疯了

#include<cstdio>
#include<iostream>
#include<cstring>
using namespace std;
int n,l,r,minn=2e9,tim[301][301],f[301][301];
int dx[5]={0,-1,0,0,1};
int dy[5]={0,0,-1,1,0};
bool used[301][301];
void make(int x,int y,int t)
{
	for(int i=0;i<=4;i++)
	if(x+dx[i]>=0&&y+dy[i]>=0) tim[x+dx[i]][y+dy[i]]=min(tim[x+dx[i]][y+dy[i]],t);
}
bool check(int x,int y,int sum)
{
	return (x>=0&&x<=l+1&&y>=0&&y<=r+1&&tim[x][y]>sum&&!used[x][y]);
}
void dfs(int x,int y,int sum)
{
	if(sum>=minn||sum>=f[x][y]) return;
	f[x][y]=sum;
	if(tim[x][y]==0x7f7f7f7f){
		minn=min(minn,sum);
		return;
	}
	if(sum>=l*r) return;
	for(int i=1;i<=4;i++){
		if(!check(x+dx[i],y+dy[i],sum+1)) continue;
		used[x][y]=true;
		dfs(x+dx[i],y+dy[i],sum+1);
		used[x][y]=false;
	}
}
int main()
{
	memset(tim,0x7f,sizeof(tim));
	memset(f,0x7f,sizeof(f));
	scanf("%d",&n);
	for(int i=1;i<=n;i++){
		int x,y,t;
		scanf("%d%d%d",&x,&y,&t);
		l=max(l,x);
		r=max(r,y);
		make(x,y,t);
	}
	dfs(0,0,0);
	if(minn==2e9) printf("-1");
	else printf("%d",minn);
	return 0;
}