PAT 甲级 1018 Public Bike Management

先用迪杰斯特拉剪枝，再dfs确定最佳方案

#include<bits/stdc++.h>
using namespace std;

typedef pair<int,int> pii;

const int N = 4010,INF = 0x3f3f3f3f;

int n,m,c,t;

int nums[N];

int head[N],dis[N],vis[N],cnt;

int send=INF,bring=INF;

struct BIAN{
	int to,next;
	int len;
}bian[N];

priority_queue<pii,vector<pii>,greater<pii> > q;

void add(int x,int y,int z){
	bian[++cnt].to=y;
	bian[cnt].next=head[x];
	bian[cnt].len=z;
	head[x]=cnt;
} 

void dij(){
	int x,y;
	memset(vis,0,sizeof vis);
	memset(dis,0x3f,sizeof dis);
	dis[0]=0;
	q.push({0,0});
	while(!q.empty()){
		x=q.top().second;
		q.pop();
		if(vis[x]) continue;
		vis[x]=1;
		for(int i=head[x];i!=-1;i=bian[i].next){
			y=bian[i].to;
			if(dis[y]>dis[x]+bian[i].len){
				dis[y]=dis[x]+bian[i].len;
				q.push({dis[y],y});
			}
		}
	}
}

int tot=0;
vector<int> path,tmp;

void dfs(int x,int cur,int mincur){
	if(x!=0){
        cur-=c-nums[x];
        mincur=min(cur,mincur);
    }
    if(x==t){
	    int sd=abs(mincur);
        int bg=sd+cur;
        if(sd<send){
            path=tmp;
            send=sd;
            bring=bg;
        }
        else if(sd==send && bg<bring){
            path=tmp;
            bring=bg;
        }
        return;
	}
	int y;
	for(int i=head[x];i!=-1;i=bian[i].next){
		y=bian[i].to;
		if(dis[x]+bian[i].len==dis[y]){
			tmp.push_back(y);
			dfs(y,cur,mincur);
			tmp.pop_back();
		}
	}
}

int main(){
	memset(head,-1,sizeof head);
	int x,y,z;
	cin>>c>>n>>t>>m;
	c/=2;
	for(int i=1;i<=n;i++) cin>>nums[i];
	for(int i=1;i<=m;i++){
		cin>>x>>y>>z;
		add(x,y,z);
		add(y,x,z);
	}
	dij();
	//cout<<dis[t]<<endl;
    tmp.push_back(0);
	dfs(0,0,0);
	cout<<send<<" ";
    cout<<"0";
	for(int i=1;i<path.size();i++) cout<<"->"<<path[i];
	cout<<" "<<bring;
	return 0;
}

标签：cnt,Management,PAT,int,bian,vis,Bike,mincur,dis
来源： https://www.cnblogs.com/xhy666/p/16245328.html