hdu-1102-Constructing Roads(Prim算法模板)

 题目链接

 /*
     Name:hdu-1102-Constructing Roads
     Copyright:
     Author:
     Date: 2018/4/18 9:35:08
     Description:
     prime算法模板
 */
 #include <iostream>
 #include <cstdio>
 #include <cstring>
 #include <utility>
 #include <vector>
 using namespace std;
 const int MAXN = , INF = 0x3f3f3f3f;
 bool v[MAXN];
 int N;
 int dis[MAXN];
 vector<pair<int ,int>> g[MAXN];
 int Prim() {
     memset(v , , sizeof(v)) ;
     for (int i=; i<=N; i++) dis[i] = INF;
     dis[] = ;
     int ans = ;
     for (int i=; i<N; i++) {
         int mark = -;
         for (int j=; j<N; j++) {
             if (!v[j]) {
                 if (mark == -) mark = j;
                 else if (dis[j]<dis[mark]) mark = j;
             }
         }
         if (mark == -) break;
         v[mark] = ;
         ans += dis[mark] ;
         for (int j=; j<g[mark].size(); ++j) {
             if (!v[g[mark][j].first]) {
                 int x =g[mark][j].first;
                 dis[x] = min(dis[x], g[mark][j].second);
             }
         }
     }
     return ans;
 }

 int main()
 {
 //    freopen("in.txt", "r", stdin);

     while (~scanf("%d", &N)) {
         for (int i=; i<; i++) {//clear
             while (!g[i].empty()) g[i].pop_back();
         }
         for (int i=; i<N; i++) {
             for (int j=; j<N; j++) {
                 int tmp;
                 scanf("%d", &tmp);
                 g[i].push_back(make_pair(j, tmp));
             }
         }
         int q;
         cin>>q;
         for (int i=; i<=q; i++) {
             int a, b;
             scanf("%d %d", &a, &b);
             a--,b--;
             g[a][b].second = g[b][a].second = ;
         }
         cout<<Prim()<<endl;
     }
     return ;
 }