2018沈阳网络赛D

k短路模板题。

 

#include <bits/stdc++.h>
#define mem(x) memset(x,0,sizeof(x))
#define mem1(x) memset(x,-1,sizeof(x))
using namespace std;
const int  M = 1005;
const int ME = 100005;
const int inf = 1000000000;
struct node
{
    int v, w, next;
}edge[ME], edge1[ME];
struct A
{
    int f, g, v;
    bool operator <(const A a)const {
        if(a.f == f) return a.g < g;
        return a.f < f;
    }
};
int e, vis[M], d[M], q[ME * 5];
int head[M], head1[M];
int n, m, s, t, k;
void init()
{
    e = 0;
    mem1(head);
    mem1(head1);
}
void insert(int x, int y, int w)
{
    edge[e].v = y;
    edge[e].w = w;
    edge[e].next = head[x];
    head[x] = e;
    edge1[e].v = x;
    edge1[e].w = w;
    edge1[e].next =head1[y];
    head1[y] = e++;
}
void spfa(int st)
{
    for(int i = 1; i <= n; i++) d[i]=inf;
    mem(vis);
    vis[st] = 0;
    int h = 0, t = 1;
    q[0] = st;
    d[st] = 0;
    while(h < t)
    {
        int u = q[h++];
        vis[u] = 0;
        for(int i = head1[u] ; i != -1; i = edge1[i].next)
        {
            int v = edge1[i].v;
            int w = edge1[i].w;
            if(d[v] > d[u] + w)
            {
                d[v] = d[u] + w;
                if(!vis[v])
                {
                    q[t++] = v;
                    vis[v] = 1;
                }
            }
        }
    }
}
int Astar(int st, int ed)
{
    int cnt = 0;
    priority_queue<A> q;
    if(st == ed) k++;
    if(d[st]==inf) return -1;
    A t, tt;
    t.v = st, t.g = 0, t.f = t.g + d[st];
    q.push(t);
    while(!q.empty())
    {
        tt = q.top();
        q.pop();
        if(tt.v == ed)
        {
            cnt++;
            if(cnt == k) return tt.g;
        }
        for(int i = head[tt.v]; i != -1; i = edge[i].next)
        {
            t.v = edge[i].v;
            t.g = tt.g + edge[i].w;
            t.f = t.g + d[t.v];
            q.push(t);
        }
    }
    return -1;
}
int main()
{
    int x, y,e, w;
    while(~scanf("%d%d", &n, &m)){
        init();
        scanf("%d%d%d%d", &s, &e, &k, &t);
        for(int i = 1; i <= m; i++)
        {
            scanf("%d%d%d", &x, &y, &w);
            insert(x, y, w);
        }
        spfa(e);
        int tmp=Astar(s,e);
        if((tmp<=t)&&(tmp!=-1))
            printf("yareyaredawa\n");
        else
            printf("Whitesnake!\n");
    }
    return 0;
}