poj 1511 -- Invitation Cards

/*    n个顶点，m条有向边    求出源点1到其他顶点的最短距离跟其他顶点到源点的最短距离之和    数据量比较到。用的邻接表存储的spfa    还有一点要注意的是dis[] 跟 ans要用__int64,    都是数据量大的原因。    这里用的是stack的spfa*/#include<iostream>#include<stdio.h>#include<stack>#include<string.h>using namespace std;const int N = 1000010;const int inf = 0x3f3f3f3f;int head[N];int outstack[N];bool vis[N];__int64 dis[N];int n,m,num_edge;typedef struct{    int end,w,nxt;} Edge;Edge edge[N];typedef struct{    int start,end,w;} Node;Node data[N];void addedge(int start,int end,int w){    edge[num_edge].end = end;    edge[num_edge].w = w;    edge[num_edge].nxt = head[start];    head[start]= num_edge++;}bool spfa(int start){    for(int i = 1 ; i <= n ; i++)    {        dis[i] = inf;        outstack[i] = 0;        vis[i] = false;    }    stack<int>s;    s.push(start);    vis[start] = true;    dis[start] = 0;    while(!s.empty())    {        int cur = s.top();        s.pop();        outstack[cur]++;        if(outstack[cur] > n)        {            return false;        }        for(int i = head[cur] ; i != -1 ; i = edge[i].nxt)        {            int x = edge[i].end;            if(dis[x] > dis[cur] + edge[i].w)            {                dis[x] = dis[cur] + edge[i].w;                if(!vis[x])                {                    vis[x] = true;                    s.push(x);                }            }        }        vis[cur] = false;    }    return true;}int main(){    int ncase;    scanf("%d",&ncase);    while(ncase--)    {        scanf("%d %d",&n,&m);        num_edge = 0;        for(int i = 0 ; i <= n ; i++)        {            head[i] = -1;        }        for(int i = 0 ; i < m ; i++)        {            scanf("%d %d %d",&data[i].start,&data[i].end,&data[i].w);            addedge(data[i].start,data[i].end,data[i].w);        }        spfa(1);        __int64 ans = 0;        for(int i = 1 ; i <= n ; i++)        {            ans += dis[i];        }        num_edge = 0;        for(int i = 0 ; i <= n ; i++)        {            head[i] = -1;        }        for(int i = 0 ; i < m ; i++)        {            addedge(data[i].end,data[i].start,data[i].w);        }        spfa(1);        for(int i = 1 ; i <= n ; i++)        {            ans += dis[i];        }        printf("%I64d\n",ans);    }    return 0;}