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先忽略航线,求出图中所有连通块,再用航线拓扑排序求出每个连通块的优先级
然后dijkstra时优先处理优先级高的块里的点就行了
ps:这题SPFA会TLE
#include <iostream> #include <cstdio> #include <cmath> #include <cstring> #include <cstdlib> #include <algorithm> #include <vector> #include <queue> #define N 25003 #define M 150004 using namespace std; inline int read(){ int ret=0;char ch=getchar(); bool flag=0; while (ch<‘0‘ || ch>‘9‘){ flag=ch==‘-‘; ch=getchar(); } while (‘0‘<=ch && ch<=‘9‘){ ret=ret*10-48+ch; ch=getchar(); } return flag?-ret:ret; } struct edge{ int adj,next,len; edge(){} edge(int _adj,int _next,int _len):adj(_adj),next(_next),len(_len){} } e[M]; int n,g[N],m,di[N]; void AddEdge(int u,int v,int w){ e[++m]=edge(v,g[u],w);g[u]=m; } int col[N],cnt; int q[N],qh,qt; int a[N],start[N]; int degree[N]; int level[N]; void bfs(){ qh=qt=0; memset(col,0,sizeof(col)); for (int i=1;i<=n;++i)if (!col[i]){ q[++qt]=i; col[i]=++cnt; start[cnt]=qt; while (qh<qt){ int u=q[++qh]; for (int i=di[u];i;i=e[i].next){ int v=e[i].adj; if (col[v]) continue; col[v]=cnt; q[++qt]=v; } } } start[cnt+1]=qt+1; for (int i=1;i<=qt;++i) a[i]=q[i]; memset(degree,0,sizeof(degree)); for (int j=1;j<=n;++j) for (int i=g[j];i!=di[j];i=e[i].next){ int v=e[i].adj; ++degree[col[v]]; } qh=qt=0; for (int i=1;i<=cnt;++i) if (!degree[i]) q[++qt]=i; int now=0; while (qh<qt){ int u=q[++qh]; level[u]=++now; for (int j=start[u];j<start[u+1];++j) for (int i=g[a[j]];i!=di[a[j]];i=e[i].next){ int v=e[i].adj; if (!--degree[col[v]]) q[++qt]=col[v]; } } } struct HeapNode{ int pos,value; HeapNode(){} HeapNode(int _pos,int _value):pos(_pos),value(_value){} }; inline bool operator >(const HeapNode &x,const HeapNode &y){ return (level[col[x.pos]]>level[col[y.pos]]||level[col[x.pos]]==level[col[y.pos]]&&x.value>y.value); } priority_queue<HeapNode,vector<HeapNode> ,greater<HeapNode> > h; int mind[N]; bool flag[N]; void dijkstra(int _s){ memset(mind,127,sizeof(mind)); memset(flag,0,sizeof(flag)); while (!h.empty()) h.pop(); h.push(HeapNode(_s,mind[_s]=0)); while (!h.empty()){ int u=h.top().pos; flag[u]=1; h.pop(); for (int i=g[u];i;i=e[i].next){ int v=e[i].adj; if (mind[v]>mind[u]+e[i].len){ mind[v]=mind[u]+e[i].len; h.push(HeapNode(v,mind[v])); } } while (!h.empty()&&flag[h.top().pos]) h.pop(); } } int main(){ n=read();int m0=read(),m1=read(),s=read(); memset(g,0,sizeof(g));m=1; while (m0--){ int u=read(),v=read(),w=read(); AddEdge(u,v,w); AddEdge(v,u,w); } for (int i=1;i<=n;++i) di[i]=g[i]; while (m1--){ int u=read(),v=read(),w=read(); AddEdge(u,v,w); } bfs(); dijkstra(s); for (int i=1;i<=n;++i) if (mind[i]>(1<<30)) puts("NO PATH"); else printf("%d\n",mind[i]); return 0; }
bzoj2200: [Usaco2011 Jan]道路和航线
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原文地址:http://www.cnblogs.com/wangyurzee7/p/5139244.html