POJ 1679 The Unique MST

#include <iostream>
#include <cstring>
#include <cstdio>
#include <algorithm>
using namespace std;
struct edge
{
int u,v,w;
}e[110*110];
int n,m,mst;
bool flag;
int fa[110];
void init()
{
flag = true;
for(int i = 0; i <= n; i++)
fa[i] = i;
}
int getfa(int x)
{
return fa[x] == x ? x : fa[x] = getfa(fa[x]);
}
bool cmp(edge a,edge b)
{
return a.w < b.w;
}
void Kruscal()
{
int num = 0;
int path[110];
mst = 0;
sort(e,e+m,cmp);
for(int i = 0; i < m; i++)
{
int x = getfa(e[i].u);
int y = getfa(e[i].v);
if(x != y)
{
fa[x] = y;
mst += e[i].w;
path[num++] = i;
}
}
if(num != n -1)
{
flag = 0;
return ;
}
for(int i = 0; i < num; i++)
{
int mst1 = 0,num1 = 0;
init();
for(int j = 0; j < m; j++)
{
if(path[i] == j) continue;
int x = getfa(e[j].u);
int y = getfa(e[j].v);
if(x != y)
{
fa[x] = y;
num1 ++;
mst1 += e[j].w;
}
}
if(num1 == num && mst1 == mst)
{
flag = false;
return ;
}
}
}
int main()
{
int t;
scanf("%d",&t);
while(t--)
{
scanf("%d%d",&n,&m);
init();
for(int i = 0; i < m; i++)
scanf("%d%d%d",&e[i].u,&e[i].v,&e[i].w);
Kruscal();
if(!flag) printf("Not Unique!\n");
else printf("%d\n",mst);
}
return 0;
}