【鏈接】 我是鏈接,點我呀:)
【題意】

在這裏輸入題意

【題解】

點可以重復走的k短路。

【代碼】

#include <bits/stdc++.h>
#define LL long long
#define rep1(i,a,b) for (int i = a;i <= b;i++)
#define rep2(i,a,b) for (int i = a;i >= b;i--)
#define all(x) x.begin(),x.end()
#define pb push_back
#define lson l,mid,rt<<1
#define ri(x) scanf("%d",&x)
#define rl(x) scanf("%lld",&x)
#define rs(x) scanf("%s",x)
#define rson mid+1,r,rt<<1|1

const double pi = acos(-1);
const int dx[4] = {0,0,1,-1};
const int dy[4] = {1,-1,0,0};
using namespace std;
#define CL(a,num)  memset(a,num,sizeof(a));
#define inf 9999999
#define eps  1e-6
const int N = 1050;
struct node
{
    int u;
    int w;
    node (int uu,int ww):u(uu),w(ww){}
};
vector<node>g[N],rg[N];
int dis[N],vis[N],tol[N];
struct cnode
{
    int u;
    int len;
    cnode (int uu,int ww):u(uu),len(ww){}
    friend bool operator < (cnode a,cnode b)
    {
        return a.len+dis[a.u]>b.len+dis[b.u];
    }
};
int n,m,s,t,k;
int T;

int A_star(int s)
{
    if(dis[s]==inf)return -1;
    priority_queue<cnode>que;
    CL(tol,0);
    que.push(cnode(s,0));
    while(!que.empty())
    {
        cnode a=que.top();que.pop();
        int u=a.u;
        int len=a.len;
        tol[u]++;
        if(tol[t]==k)return len;

        rep1(i,0,(int)g[u].size()-1){
            node b=g[u][i];
            int v=b.u;
            que.push(cnode(v,len+b.w));
        }
    }
    return -1;
}

void spfa(int s)
{
    int i;
    for(i=0;i<=n;i++)
    {
        dis[i]=inf;
        vis[i]=0;
    }
    dis[s]=0;
    queue<int>que;
    que.push(s);
    while(!que.empty())
    {
        int u=que.front();que.pop();
        vis[u]=0;
        //if (dis[u]>T) continue;
        rep1(i,0,(int)rg[u].size()-1){
            node b=rg[u][i];
            int v=b.u;
            if(dis[v]>dis[u]+b.w)
            {
                dis[v]=dis[u]+b.w;
                if(!vis[v])
                {
                    vis[v]=1;
                    que.push(v);
                }
            }
        }
    }
}

int main()
{
    while(~scanf("%d%d",&n,&m))
    {
        int x,y,z;
        rep1(i,0,n){
            g[i].clear();rg[i].clear();
        }
        ri(s);ri(t);ri(k);ri(T);
        rep1(i,0,m-1){
            ri(x);ri(y);ri(z);
            g[x].push_back(node(y,z));rg[y].push_back(node(x,z));
        }

        spfa(t);
        int ans=A_star(s);
        if (ans==-1 || ans>T){
            puts("Whitesnake!");
        }else{
            puts("yareyaredawa");
        }
    }
    return 0;
}
 

【 ACM-ICPC 2018 沈陽賽區網絡預賽 D】Made In Heaven