洛谷 P1195 口袋的天空 解题思路: AC代码:

题目传送门

本题直接跑一遍Kruskal,当成功加入n-k条边时即为目标状态。

AC代码:

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<algorithm>
 4 
 5 using namespace std;
 6 
 7 int n,m,k,fa[1001],sum,ans;
 8 struct kkk {
 9     int qd,zd,v;
10 }e[10001];
11 
12 bool cmp(kkk a,kkk b) {
13     return a.v < b.v;
14 }
15 
16 int find_father(int x) {
17     if(fa[x] == x) return x;
18     return fa[x] = find_father(fa[x]);
19 }
20 
21 int main() {
22     scanf("%d%d%d",&n,&m,&k);
23     for(int i = 1;i <= m; i++) 
24         scanf("%d%d%d",&e[i].qd,&e[i].zd,&e[i].v);
25     for(int i = 1;i <= n; i++) 
26         fa[i] = i;
27     sort(e+1,e+1+m,cmp);
28     for(int i = 1;i <= m; i++) {
29         int be,end;
30         be = e[i].qd;
31         end = e[i].zd;
32         be = find_father(be);
33         end = find_father(end);
34         if(be == end) continue;
35         fa[be] = end;
36         sum++;
37         ans += e[i].v;
38         if(sum == n - k) {
39             printf("%d",ans);
40             return 0;
41         }
42     }
43     printf("No Answer");
44     return 0;
45 }