hdu 1863 畅通工程

/*

就是1232，,133的组合

*/

#include<iostream>
#include<vector>
#include<algorithm>
using namespace std;
int ch[102];

struct Line
{
	int s, e;
	int v;
}L;

vector<Line> vec;

bool cmp(Line x, Line y) { return x.v < y.v; }

int Find(int x)
{
	while(x != ch[x])
		x = ch[x];
	return x;
}

int main()
{
	int n, m;
	while(scanf("%d%d", &n, &m)  && n)
	{
		int i, j;
		vec.clear();
		for( i=0; i <= m; i++ )
			ch[i] = i;
		for( i=0; i < n; i++ )
		{
			scanf("%d%d%d", &L.s, &L.e, &L.v);
			vec.push_back(L);
		}
		sort(vec.begin(), vec.end(), cmp);
		int sum=0;
		for( i=0; i < vec.size(); i++ )
		{
			L = vec.at(i);
			int x = Find(L.s);
			int y = Find(L.e);
			if(x > y)
				ch[x] = y;
			else if(x < y)
				ch[y] = x;
			else continue;
			sum += L.v;
		}
		int p=0;
		for( i=1; i <= m; i++ )
		{
			if(ch[i] == i)
				p++;
		}
		if(p > 1)
			printf("?\n");
		else
			printf("%d\n", sum);
		
	}
	return 0;
}