bzoj 2763 [JLOI2011]飞行路线 Dijikstra 分层

k<=10，所以每用一次机会就跳到一个新图中，

每一个图按原图建边，相邻两图中建边权为0的边

补一补dj，好像我以前觉得dj特别难，hhhhh

#include<cstdio>#include<cstring>#include<algorithm>#include<cmath>#include<queue>#include<iostream>#define N 500500using namespace std;int n,m,k,S,T;struct point{    int st,dis;    bool operator < (const point &a)const{        return dis>a.dis;    }}p[N];int e=1,head[N],dis[N];bool bo[N];struct edge{    int u,v,w,next;}ed[5000500];void add(int u,int v,int w){    ed[e].u=u; ed[e].v=v; ed[e].w=w;    ed[e].next=head[u]; head[u]=e++;}priority_queue<point> q;int dijkstra(){    memset(dis,0x7f,sizeof dis);    memset(bo,0,sizeof bo);    dis[S]=0;q.push((point){S,0});    while(!q.empty()){        point now=q.top();q.pop();        if(bo[now.st]) continue;        bo[now.st]=1;        for(int i=head[now.st];i;i=ed[i].next)            if(dis[now.st]+ed[i].w<dis[ed[i].v]){                dis[ed[i].v]=dis[now.st]+ed[i].w;                q.push((point){ed[i].v,dis[ed[i].v]});            }    }    int ans=0x7fffffff;    for(int i=0;i<=k;i++)        ans=min(ans,dis[i*n+T]);    return ans;     }int main(){    scanf("%d%d%d",&n,&m,&k);    scanf("%d%d",&S,&T);S++;T++;    int u,v,w;    for(int i=1;i<=m;i++){        scanf("%d%d%d",&u,&v,&w);        u++;v++;        for(int j=0;j<=k;j++){            add(j*n+u,j*n+v,w),add(j*n+v,j*n+u,w);            if(j<k)add(j*n+u,(j+1)*n+v,0),add(j*n+v,(j+1)*n+u,0);        }    }    int ans=dijkstra();    printf("%d\n",ans);    return 0;}