# Light OJ 1123 – Trail Maintenance

Problem Link : http://www.lightoj.com/volume_showproblem.php?problem=1123

```
/*
+-+ +-+ +-+
|R| |.| |S|
+-+ +-+ +-+
*/

#include &lt;bits/stdc++.h&gt;

#define pii             pair &lt;int,int&gt;
#define sc              scanf
#define pf              printf
#define Pi              2*acos(0.0)
#define ms(a,b)         memset(a, b, sizeof(a))
#define pb(a)           push_back(a)
#define MP              make_pair
#define db              double
#define ll              long long
#define EPS             10E-10
#define ff              first
#define ss              second
#define sqr(x)          (x)*(x)
#define D(x)            cout&lt;&lt;#x &quot; = &quot;&lt;&lt;(x)&lt;&lt;endl
#define VI              vector &lt;int&gt;
#define DBG             pf(&quot;Hi\n&quot;)
#define MOD             100007
#define MAX             10000
#define CIN             ios_base::sync_with_stdio(0); cin.tie(0)
#define SZ(a)           (int)a.size()
#define sf(a)           scanf(&quot;%d&quot;,&amp;a)
#define sff(a,b)        scanf(&quot;%d%d&quot;,&amp;a,&amp;b)
#define sfff(a,b,c)     scanf(&quot;%d%d%d&quot;,&amp;a,&amp;b,&amp;c)
#define loop(i,n)       for(int i=0;i&lt;n;i++)
#define REP(i,a,b)      for(int i=a;i&lt;b;i++)
#define TEST_CASE(t)    for(int z=1;z&lt;=t;z++)
#define PRINT_CASE      printf(&quot;Case %d:\n&quot;,z)
#define all(a)          a.begin(),a.end()
#define intlim          2147483648
#define inf             1000000
#define ull             unsigned long long

using namespace std;

struct data
{
int u,v,w;
bool operator&lt; (const data&amp; p)const
{
return w&lt;p.w;
}
data(int x,int y, int z)
{
u=x,v=y,w=z;
}
};

vector&lt;data&gt;edge;
int n,m,cnt=0;
int par[210];

int find_par(int n)
{
return par[n]=(par[n]==n)?n:find_par(par[n]);
}

int mst()
{
int cnt=0,sum=0;
sort(all(edge));
vector&lt;data&gt;temp;
for(int i=0; i&lt;SZ(edge); i++)
{
int u=find_par(edge[i].u);
int v=find_par(edge[i].v);
if(u!=v)
{
cnt++;
par[u]=v;
sum+=edge[i].w;
temp.pb(edge[i]);
if(cnt==n-1)
break;
}
}
edge.clear();
edge=temp;
if(cnt==n-1) return sum;
return -1;
}

int main()
{
///freopen(&quot;in.txt&quot;,&quot;r&quot;,stdin);
///freopen(&quot;out.txt&quot;,&quot;w&quot;,stdout);
int t;
sf(t);
TEST_CASE(t)
{
sff(n,m);
PRINT_CASE;
while(m--)
{
int x,y,z;
sfff(x,y,z);
edge.pb(data(x,y,z));
loop(i,n+5)
par[i]=i;
pf(&quot;%d\n&quot;,mst());
}
edge.clear();
}
return 0;
}

```
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