BZOJ P1579 [Usaco2009 Feb]Revamping Trails 道路升级【多维最短路】

#include <queue>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
#define ll long long
#define rep(i,x,y) for(ll i=(x);i<=(y);i++)
#define repl(i,x,y) for(ll i=(x);i<(y);i++)
#define repd(i,x,y) for(ll i=(x);i>=(y);i--)
using namespace std;

const ll T=25;
const ll N=1e4+5;
const ll M=5e4+5;
const ll Inf=1e18;

ll n,m,t,vis[N][T],dis[N][T];
ll cnt,to[M<<1],edge[M<<1],nxt[M<<1],head[N];

struct node {
	ll id,del,dis;
};

inline ll read() {
    ll x=0;char ch=getchar();bool f=0;
    while(ch>'9'||ch<'0'){if(ch=='-')f=1;ch=getchar();}
    while(ch>='0'&&ch<='9'){x=(x<<1)+(x<<3)+ch-'0';ch=getchar();}
    return f?-x:x;
}

void ins(ll x,ll y,ll z) {
	to[++cnt]=y;edge[cnt]=z;nxt[cnt]=head[x];head[x]=cnt;
}

void dij(ll s) {
	priority_queue<node>q;
	rep(i,1,n) rep(j,0,t) dis[i][j]=Inf;
	
	dis[s][0]=0;q.push(node{s,0,0});
	 
	while(q.size()) {
		ll x=q.top().id,del=q.top().del;q.pop();
		
		if(vis[x][del]) continue;
		
		vis[x][del]=1;
		
		for(ll i=head[x];i;i=nxt[i]) {
			ll y=to[i],z=edge[i];
			
			if(dis[y][del]>dis[x][del]+z) {
				dis[y][del]=dis[x][del]+z;q.push(node{y,del,dis[y][del]});
			}
			if(dis[y][del+1]>dis[x][del]&&del+1<=t) {
				dis[y][del+1]=dis[x][del];q.push(node{y,del+1,dis[y][del+1]});
			}		
		}
	}
}

bool operator < (node p,node q) {
	return p.dis>q.dis;
}

int main() {
	n=read(),m=read(),t=read();
	
	rep(i,1,m) {
		ll x=read(),y=read(),z=read();ins(x,y,z),ins(y,x,z);
	}
	
	dij(1);
	
	printf("%lld",dis[n][t]);

	return 0;
}