poj1734 Sightseeing trip

无向图最小环

#include <iostream>
#include <cstring>
#include <cstdio>
#include <vector>
using namespace std;
typedef long long ll;
int n, m, uu, vv, ww, a[105][105], b[105][105], pos[105][105], ans;
const int oo=0x3f3f3f3f;
vector<int> vec;
void dig(int x, int y){
	if(pos[x][y]==0)	return ;
	dig(x, pos[x][y]);
	vec.push_back(pos[x][y]);
	dig(pos[x][y], y);
}
int main(){
	cin>>n>>m;
	memset(a, 0x3f, sizeof(a));
	memset(b, 0x3f, sizeof(b));
	for(int i=1; i<=n; i++)
		a[i][i] = b[i][i] = 0;
	for(int i=1; i<=m; i++){
		scanf("%d %d %d", &uu, &vv, &ww);
		a[uu][vv] = a[vv][uu] = b[uu][vv] = b[vv][uu] = min(a[uu][vv], ww);
	}
	ans = oo;
	for(int k=1; k<=n; k++){
		for(int i=1; i<k; i++)
			for(int j=i+1; j<k; j++){
				if((ll)b[i][j]+a[j][k]+a[k][i]<ans){
					ans = b[i][j] + a[j][k] + a[k][i];
					vec.clear();
					vec.push_back(i);
					dig(i, j);
					vec.push_back(j);
					vec.push_back(k);
				}
			}
		for(int i=1; i<=n; i++)
			for(int j=1; j<=n; j++)
				if(b[i][j]>b[i][k]+b[k][j]){
					b[i][j] = b[i][k] + b[k][j];
					pos[i][j] = k;
				}
	}
	if(ans==oo)	printf("No solution.
");
	else{
		for(int i=0; i<vec.size(); i++)
			printf("%d ", vec[i]);
		printf("
");
	}
	return 0;
}