Poj 1679 The Unique MST 判断最小生成树是否唯一

#include <cstdio>
#include <cstring>
#include <cmath>
#include <algorithm>
#include <climits>
#include <string>
#include <iostream>
#include <map>
#include <cstdlib>
#include <list>
#include <set>
#include <queue>
#include <stack>

using namespace std;

typedef long long LL;
const int maxn = 105;
const int maxk = 105 * 105;
struct Edge {
int u,v,w;
bool operator < (const Edge &x) const {
return w < x.w;
}
};
Edge e[maxk];
bool del[maxk],equ[maxk],used[maxk];
int n,m,fa[maxn];

int findp(int x) {
return x == fa[x] ? x : fa[x] = findp(fa[x]);
}

int Kruskal(bool flag) {
int ret = 0;
for(int i = 1;i <= n;i++) fa[i] = i;
for(int i = 0;i < m;i++) if(!del[i]) {
int pa = findp(e[i].u),pb = findp(e[i].v);
if(pa == pb) continue;
if(flag) used[i] = true;
fa[pa] = pb;
ret += e[i].w;
}
return ret;
}

int main() {
int T; scanf("%d",&T);
while(T--) {
scanf("%d%d",&n,&m);
memset(del,0,sizeof(del));
memset(equ,0,sizeof(equ));
memset(used,0,sizeof(used));
for(int i = 0;i < m;i++) {
scanf("%d%d%d",&e[i].u,&e[i].v,&e[i].w);
}
sort(e,e + m);
for(int i = 1;i < m;i++) {
if(e[i].w == e[i - 1].w) {
equ[i] = equ[i - 1] = true;
}
}
int first = Kruskal(1);
bool unique = true;
for(int i = 0;i < m;i++) if(used[i] && equ[i]) {
del[i] = true;
int now = Kruskal(0);
if(now == first) {
unique = false;
break;
}
}
if(unique) printf("%d\n",first);
else puts("Not Unique!");
}
return 0;
}