洛谷 [P2483] [模板] k短路

人生中的第一道黑题。。。

其实就是k短路模板

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cmath>
#include <algorithm>
#include <cstdlib>
#include <queue>
using namespace std;
const int MAXN=400005;
int init(){
	int rv=0,fh=1;
	char c=getchar();
	while(c<'0'||c>'9'){
		if(c=='-') fh=-1;
		c=getchar();
	}
	while(c>='0'&&c<='9'){
			rv=(rv<<1)+(rv<<3)+c-'0';
			c=getchar();
		}
		return rv*fh;
	}
	int m,n,head1[MAXN],nume,head[MAXN];
	double tot,dis[MAXN];
	struct edge{
		int to,nxt;
		double dis;
	}e[MAXN],e1[MAXN];
	void adde1(int from,int to,double dis){
		e1[++nume].to=to;
		e1[nume].dis=dis;
		e1[nume].nxt=head1[from];
		head1[from]=nume;
	}
	void adde(int from,int to,double dis){
		e[++nume].to=to;
		e[nume].dis=dis;
		e[nume].nxt=head[from];
		head[from]=nume;
	}
	struct cmp{
		bool operator ()(const int &a,const int &b) const{
			return dis[a]>dis[b];
		}
	};
	void dij(){
		priority_queue <int,vector<int> ,cmp> q;
		q.push(n);
		memset(dis,0x7f,sizeof(dis));
		dis[n]=0;
		while(!q.empty()){
			int u=q.top();q.pop();
			for(int i=head1[u];i;i=e1[i].nxt){
				int v=e1[i].to;
				if(dis[v]>dis[u]+e1[i].dis){
					dis[v]=dis[u]+e1[i].dis;
					q.push(v);
				}
			}
		}
	}
	struct node{
		int v;
		double f,g;
		bool operator < (const node &a)const{
			if(this->f==a.f) return (this->g)>a.g;
			return (this->f)>a.f;
	}
};
void A_star(){
	node s;
	int cnt=0;
	s.v=1;s.f=dis[1];s.g=0.0;
	priority_queue <node>q;
	q.push(s);
	while(!q.empty()){
		node u=q.top();q.pop();//cout<<u.v<<" "<<u.f<<" "<<u.g<<endl;
		if(u.v==n){
			//cout<<tot<<endl;
			if(tot>=u.g) tot-=u.g,cnt++;
			else{
				cout<<cnt<<endl;
				return;
			}
		}
		for(int i=head[u.v];i;i=e[i].nxt){
			node v;
			v.v=e[i].to;
			v.g=u.g+e[i].dis;
			v.f=v.g+dis[e[i].to];
			//if(v.v==n) cout<<v.f<<endl;
			q.push(v);
		}
	}
	cout<<1<<endl;
}
int main(){
	n=init();m=init();scanf("%lf",&tot);
	for(int i=1;i<=m;i++){
		int u=init(),v=init();
		double di;
		scanf("%lf",&di);
		adde1(v,u,di);
	}
	dij();
//	cout<<dis[1]<<endl;
	nume=0;
	for(int i=1;i<=n;i++){
		for(int j=head1[i];j;j=e1[j].nxt){
			int v=e1[j].to;
			adde(v,i,e1[j].dis);
		}
	}
	//cout<<e[1].dis<<endl;
//	for(int i=head[1];i;i=e[i].nxt) cout<<e[i].to<<endl;
	A_star();
	return 0;
}