洛谷P2895 [USACO08FEB]Meteor Shower S

搜索边界可以比300大

#include
#include
#include
using namespace std;
queue<pair<int,int> >qe;
int count;
int ans = 1e8;
int dx[] = {0,1,-1,0,0};
int dy[] = {0,0,0,1,-1};
int a[350][305] = {0};
int p[350][350];
int t[350][350];
int m,x,y,t2;
void change(int x1,int y1,int t1){
	if(t1 == 0)t1 = -1;
	int i;
	for(i = 0; i <= 4; ++i){
		if(x1+dx[i] >= 0 && x1+dx[i] <= 305 && y1+dy[i] >= 0 && y1+dy[i] <= 305)
			if(!a[x1+dx[i]][y1+dy[i]] || a[x1+dx[i]][y1+dy[i]] > t1)a[x1+dx[i]][y1+dy[i]] = t1;
	}
	return ;
}
void run(){
	int i;
	int x1 = qe.front().first;
	int y1 = qe.front().second;
	for(i = 1; i <= 4; ++i){
		if(x1+dx[i] >= 0 && x1+dx[i] <= 305 && y1+dy[i] >= 0 && y1+dy[i] <= 305 && !p[x1+dx[i]][y1+dy[i]]){
			if(!a[x1+dx[i]][y1+dy[i]]){
				cout << t[x1][y1] + 1 << endl;
				return ;
			}
			if(a[x1+dx[i]][y1+dy[i]] > t[x1][y1]+1 && a[x1+dx[i]][y1+dy[i]]){
				qe.push(make_pair(x1+dx[i],y1+dy[i]));
				t[x1+dx[i]][y1+dy[i]] = t[x1][y1] + 1;
				p[x1+dx[i]][y1+dy[i]] = 1;
			}
		}
	}
	qe.pop();
	if(!qe.empty())run();
	else{
		cout << -1 << endl;
	}
	return ;
}
int main(){
	cin >> m;
	while(m--){
		cin >> x >> y >> t2;
		change(x,y,t2);
	}
	qe.push(make_pair(0,0));
	p[0][0] = 1;
	run();
	return 0;
}