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[dijkstra]

2015-09-14 22:12 323 查看
#include<bits/stdc++.h>
using namespace std;
const int INF = 0x7f7f7f7f;
const int maxn = 10000;

struct Edge{
    int from,to,dist;
    Edge(int u,int v,int d):from(u),to(v),dist(d) {}
};
struct HeapNode{
    int d,u;
    bool operator < (const HeapNode& rhs) const {
        return d >rhs.d;
    }
};
struct Dijkstra{
    int n,m;
    vector<Edge> edges;
    vector<int> G[maxn];
    bool done[maxn];    //是否已永久标号
    int d[maxn]; //s到各个点的距离
    int p[maxn]; //最短路中的上一条弧

    void init(int n){

        for(int i=0;i<n;i++) G[i].clear();
        edges.clear();
    }

    void AddEdge(int from,int to,int dist){
        edges.push_back(Edge(from,to,dist));
        m=edges.size();
        G[from].push_back(m-1);
    }

    void dijkstra(int s){
        priority_queue<HeapNode> Q;
        for(int i=0;i<n;i++) d[i]=INF;
        d[s]=0;
        memset(done,0,sizeof(done));
        Q.push((HeapNode){0,s});
        while(!Q.empty()){
            HeapNode x=Q.top();
            Q.pop();
            int u=x.u;
            if(done[u]) continue;
            done[u]=true;
            for(int i=0;i<G[u].size();i++){
                Edge& e=edges[ G[u][i] ];
                if(d[e.to] > d[u] + e.dist){
                    d[e.to]=d[u]+e.dist;
                    p[e.to]=G[u][i];
                    Q.push((HeapNode){d[e.to],e.to});
                }
            }
        }
    }

};
int main()
{
    Dijkstra a;
    int M;
    scanf("%d%d",&a.n,&M);
    a.init(a.n);
    while(M--){
        int x,y,z;
        scanf("%d%d",&x,&y);
//        printf("%d%d%d\n",x,y,);
        a.AddEdge(x-1,y-1,1);
    }
    a.dijkstra(0);
    for(int i=0;i<=a.n;i++)
    printf("%d\n",a.d[i]);
    return 0;
}
/*
6 6
1 2
2 3
1 3
2 5
2 6
3 4
*/
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