[POJ1679]The Unique MST 次小生成树

  1 #include <algorithm>
  2 #include <iostream>
  3 #include <iomanip>
  4 #include <cstring>
  5 #include <climits>
  6 #include <complex>
  7 #include <fstream>
  8 #include <cassert>
  9 #include <cstdio>
 10 #include <bitset>
 11 #include <vector>
 12 #include <deque>
 13 #include <queue>
 14 #include <stack>
 15 #include <ctime>
 16 #include <set>
 17 #include <map>
 18 #include <cmath>
 19 
 20 using namespace std;
 21 
 22 typedef struct Node {
 23     int u;
 24     int v;
 25     int w;
 26 }Node;
 27 
 28 bool cmp(Node n1, Node n2) {
 29     return n1.w < n2.w;
 30 }
 31 
 32 const int maxn = 111;
 33 Node node[6666];
 34 int vis[maxn];
 35 int n, m, u, v, w;
 36 int pre[maxn];
 37 int cnt, dig, flag, ans;
 38 
 39 void init() {
 40     for(int i = 0; i <= maxn; i++) {
 41         pre[i] = i;
 42     }
 43 }
 44 
 45 int find(int x) {
 46     return x == pre[x] ? x : pre[x] = find(pre[x]);
 47 }
 48 
 49 void unite(int x, int y) {
 50     x = find(x);
 51     y = find(y);
 52     if(x != y) pre[y] = x;
 53 }
 54 
 55 int main() {
 56     // freopen("in", "r", stdin);
 57     int T;
 58     scanf("%d", &T);
 59     while(T--) {
 60         init();
 61         memset(vis, 0, sizeof(vis));
 62         memset(node, 0, sizeof(node));
 63         dig = 0;
 64         cnt = 0;
 65         flag = 0;
 66         scanf("%d %d", &n, &m);
 67         for(int i = 0; i < m; i++) {
 68             scanf("%d %d %d", &u, &v, &w);
 69             node[i].u = u;
 70             node[i].v = v;
 71             node[i].w = w;
 72         }
 73         sort(node, node+m, cmp);
 74         for(int i = 0; i < m && cnt < n; i++) {
 75             if(find(node[i].u) != find(node[i].v)) {
 76                 unite(node[i].u, node[i].v);
 77                 vis[cnt++] = i;
 78                 dig += node[i].w;
 79             }
 80         }
 81         ans = dig;
 82 
 83         for(int i = 1; i < n; i++) {
 84             init();
 85             cnt = n - 1;
 86             dig = 0;
 87             for(int j = 0; j < m && cnt; j++) {
 88                 if(vis[i] != j && find(node[j].u) != find(node[j].v)) {
 89                     unite(node[j].u, node[j].v);
 90                     dig += node[j].w;
 91                     cnt--;
 92                 }
 93             }
 94             if(cnt == 0 && dig == ans) {
 95                 flag = 1;
 96                 break;
 97             }
 98         }
 99 
100         if(flag) printf("Not Unique!\n");
101         else printf("%d\n", ans);
102     }
103 }