poj 1511 优先队列优化dijkstra *

题意：两遍最短路

链接：点我

注意结果用long long

#include<cstdio>
#include<iostream>
#include<algorithm>
#include<cstring>
#include<cmath>
#include<queue>
#include<map>
using namespace std;
#define MOD 1000000007
#define pb(a) push_back(a)
const int INF=0x3f3f3f3f;
const double eps=1e-5;
typedef long long ll;
#define cl(a) memset(a,0,sizeof(a))
#define ts printf("*****
");
const int MAXN=1000005;
int p[MAXN],q[MAXN],w[MAXN];
int n,m,tt,cnt;
/*
* 使用优先队列优化Dijkstra算法
* 复杂度O(ElogE)
* 注意对vector<Edge>E[MAXN]进行初始化后加边
*/
struct qnode
{
int v;
int c;
qnode(int _v=0,int _c=0):v(_v),c(_c){}
bool operator <(const qnode &r)const
{
return c>r.c;
}
};
struct Edge
{
int v,cost;
Edge(int _v=0,int _cost=0):v(_v),cost(_cost){}
};
vector<Edge>E[MAXN];
bool vis[MAXN];
int dist[MAXN];
void Dijkstra(int n,int start)//点的编号从1开始
{
memset(vis,false,sizeof(vis));
for(int i=1;i<=n;i++)dist[i]=INF;
priority_queue<qnode>que;
while(!que.empty())que.pop();
dist[start]=0;
que.push(qnode(start,0));
qnode tmp;
while(!que.empty())
{
tmp=que.top();
que.pop();
int u=tmp.v;
if(vis[u])continue;
vis[u]=true;
for(int i=0;i<E[u].size();i++)
{
int v=E[tmp.v][i].v;
int cost=E[u][i].cost;
if(!vis[v]&&dist[v]>dist[u]+cost)
{
dist[v]=dist[u]+cost;
que.push(qnode(v,dist[v]));
}
}
}
}
void addedge(int u,int v,int w)
{
E[u].push_back(Edge(v,w));
}
int main()
{
    int i,j,k;
    #ifndef ONLINE_JUDGE
    freopen("1.in","r",stdin);
    #endif
    scanf("%d",&tt);
    while(tt--)
    {
        scanf("%d%d",&n,&m);
        for(i=0;i<=n;i++)    E[i].clear();
        for(i=0;i<m;i++)
        {
            scanf("%d%d%d",&p[i],&q[i],&w[i]);
            addedge(p[i],q[i],w[i]);
        }
        Dijkstra(n,1);
        ll sum=0;
        for(i=2;i<=n;i++)
        {
            sum+=dist[i];
        }
        for(i=0;i<=n;i++)    E[i].clear();
        for(i=0;i<m;i++)    addedge(q[i],p[i],w[i]);
        Dijkstra(n,1);
        for(i=2;i<=n;i++)
        {
            sum+=dist[i];
        }
        printf("%I64d
",sum);
    }
}