Prim && Kruskal

Electrification Plan

Prim

 #include<iostream>
 #include<cstring>
 using namespace std;
 const int INF = 0x3f3f3f3f;
 const int N = ;
 int n, k;
 int dis[N], ct[N][N], vis[N];
 
 int Prim()
 {
     int ans = ;
     memset(vis, , sizeof(vis));
     /*
         for(int i = 1; i <= n; i++)
             dis[i] = ct[1][i];
         vis[1] = 1;
     */
     while()
     {
         int v = -;
         for(int i = ; i <= n; i++)
         {
             if(!vis[i] && (v == -||dis[v]>dis[i])) v = i;
         }
         if(v == -) break;
         ans += dis[v];
         vis[v] = ;
         for(int i = ; i <= n; i++)
             if(!vis[i])
                 dis[i] = min(dis[i], ct[v][i]);
     }
     return ans;
 }
 int main()
 {
     ios::sync_with_stdio(false);
     cin.tie();
     cout.tie();
     cin >> n >> k;
     memset(dis, INF, sizeof(dis));
     int tmp;
     while(k--)
     {
         cin >> tmp;
         dis[tmp] = ;
     }
     for(int i = ; i <= n; i++)
         for(int j = ; j <= n; j++)
             cin >> ct[i][j];
     cout << Prim() << endl;
     return ;
 }

Kruskal

 #include<iostream>
 #include<algorithm>
 #include<cstring>
 using namespace std;
 const int N = ;
 struct node
 {
     int l, r, c;
     bool operator < (const node & x)
     {
         return c < x.c;
     }
 }A[N*N];
 int pre[N];
 int Find(int x)
 {
     if(x == pre[x]) return x;
     return pre[x] = Find(pre[x]);
 }
 int main()
 {
     ios::sync_with_stdio(false);
     cin.tie();
     cout.tie();
     int n, m;
     cin >> n >> m;
     for(int i = ; i <= n; i++)
         pre[i] = i;
     int t, tmp;
     cin >> t;
     m--;
     while(m--)
     {
         cin >> tmp;
         t = Find(t);
         tmp = Find(tmp);
         pre[tmp] = t;
     }
     int cnt = ;
     for(int i = ; i <= n; i++)
     {
         for(int j = ; j <= n; j++)
         {
             cin >> tmp;
             if(i <= j) continue;
             A[cnt].l = i, A[cnt].r = j, A[cnt++].c = tmp;
         }
     }
     int ans = ;
     sort(A, A+cnt);
     for(int i = ; i < cnt; i++)
     {
         int x =A[i].l, y = A[i].r, ct = A[i].c;
         x = Find(x), y = Find(y);
         if(x == y) continue;
         pre[y] = x;
         ans += ct;
     }
     cout << ans << endl;
     return ;
 }