【luogu P3946 ことりのおやつ】 题解

题目链接：https://www.luogu.org/problemnew/show/P3946

交好几遍是因为虽然能过一直有提醒..强迫症qwq

#include <bits/stdc++.h>
#define ll long long
using namespace std;
const int maxn = 5 * 1e6 + 10;
ll n, m, s, t, g, q;
ll dis[maxn], h[maxn], l[maxn];
bool vis[maxn];
struct edge{
	ll from, to, next, len;
}e[maxn<<2];
ll head[maxn], cnt;
queue<int> Q;
void add(ll u, ll v, ll w)
{
	e[++cnt].from = u;
	e[cnt].len = w;
	e[cnt].next = head[u];
	e[cnt].to = v;
	head[u] = cnt;
}
void SPFA()
{
	while(!Q.empty())
	{
		ll now = Q.front(); Q.pop();
		vis[now] = 0;
		for(int i = head[now]; i != -1; i = e[i].next)
		{
			//cout<<e[i].from<<" "<<e[i].to<<endl;
			if(e[i].to == t && dis[e[i].to] > dis[now] + e[i].len)
			{
				dis[e[i].to] = dis[now] + e[i].len;
				if(!vis[e[i].to])
				{
					Q.push(e[i].to);
					vis[e[i].to] = 1;
				}
				continue;
			}
			if(dis[e[i].to] > dis[now] + e[i].len && (dis[e[i].from] + e[i].len) * q + h[e[i].to] <= l[e[i].to])
			{
				dis[e[i].to] = dis[now] + e[i].len;
				if(!vis[e[i].to])
				{
					Q.push(e[i].to);
					vis[e[i].to] = 1;
				}
			}
		}
	}
}
int main()
{
	memset(dis, 127, sizeof(dis));
	memset(head, -1, sizeof(head));
	scanf("%lld%lld%lld%lld%lld%lld",&n,&m,&s,&t,&g,&q);
	for(int i = 1; i <= n; i++)
	scanf("%lld%lld",&h[i],&l[i]);
	for(int i = 1; i <= m; i++)
	{
		ll u, v, w;
		scanf("%lld%lld%lld",&u,&v,&w);
		add(u, v, w);
		add(v, u, w);
	}
	dis[s] = 0, vis[s] = 1, Q.push(s);
	SPFA();
	if(dis[t] <= g)
	printf("%lld",dis[t]);
	else
	printf("wtnap wa kotori no oyatsu desu!\n");
	return 0;
}