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

  1 #include<cstdio>
  2 #include<iostream>
  3 #include<algorithm>
  4 #include<cstring>
  5 #include<cmath>
  6 #include<queue>
  7 #include<map>
  8 using namespace std;
  9 #define MOD 1000000007
 10 #define pb(a) push_back(a)
 11 const int INF=0x3f3f3f3f;
 12 const double eps=1e-5;
 13 typedef long long ll;
 14 #define cl(a) memset(a,0,sizeof(a))
 15 #define ts printf("*****\n");
 16 const int MAXN=1000005;
 17 int p[MAXN],q[MAXN],w[MAXN];
 18 int n,m,tt,cnt;
 19 /*
 20 * 使用优先队列优化Dijkstra算法
 21 * 复杂度O(ElogE)
 22 * 注意对vector<Edge>E[MAXN]进行初始化后加边
 23 */
 24 struct qnode
 25 {
 26 int v;
 27 int c;
 28 qnode(int _v=0,int _c=0):v(_v),c(_c){}
 29 bool operator <(const qnode &r)const
 30 {
 31 return c>r.c;
 32 }
 33 };
 34 struct Edge
 35 {
 36 int v,cost;
 37 Edge(int _v=0,int _cost=0):v(_v),cost(_cost){}
 38 };
 39 vector<Edge>E[MAXN];
 40 bool vis[MAXN];
 41 int dist[MAXN];
 42 void Dijkstra(int n,int start)//点的编号从1开始
 43 {
 44 memset(vis,false,sizeof(vis));
 45 for(int i=1;i<=n;i++)dist[i]=INF;
 46 priority_queue<qnode>que;
 47 while(!que.empty())que.pop();
 48 dist[start]=0;
 49 que.push(qnode(start,0));
 50 qnode tmp;
 51 while(!que.empty())
 52 {
 53 tmp=que.top();
 54 que.pop();
 55 int u=tmp.v;
 56 if(vis[u])continue;
 57 vis[u]=true;
 58 for(int i=0;i<E[u].size();i++)
 59 {
 60 int v=E[tmp.v][i].v;
 61 int cost=E[u][i].cost;
 62 if(!vis[v]&&dist[v]>dist[u]+cost)
 63 {
 64 dist[v]=dist[u]+cost;
 65 que.push(qnode(v,dist[v]));
 66 }
 67 }
 68 }
 69 }
 70 void addedge(int u,int v,int w)
 71 {
 72 E[u].push_back(Edge(v,w));
 73 }
 74 int main()
 75 {
 76     int i,j,k;
 77     #ifndef ONLINE_JUDGE
 78     freopen("1.in","r",stdin);
 79     #endif
 80     scanf("%d",&tt);
 81     while(tt--)
 82     {
 83         scanf("%d%d",&n,&m);
 84         for(i=0;i<=n;i++)    E[i].clear();
 85         for(i=0;i<m;i++)
 86         {
 87             scanf("%d%d%d",&p[i],&q[i],&w[i]);
 88             addedge(p[i],q[i],w[i]);
 89         }
 90         Dijkstra(n,1);
 91         ll sum=0;
 92         for(i=2;i<=n;i++)
 93         {
 94             sum+=dist[i];
 95         }
 96         for(i=0;i<=n;i++)    E[i].clear();
 97         for(i=0;i<m;i++)    addedge(q[i],p[i],w[i]);
 98         Dijkstra(n,1);
 99         for(i=2;i<=n;i++)
100         {
101             sum+=dist[i];
102         }
103         printf("%I64d\n",sum);
104     }
105 }