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 }