2016湘潭邀请赛 xtu1245
Hamiltonian Path
In ICPCCamp, there are n cities and m directed roads between cities. The i-th road going from the ai-th city to the bi-th city is ci kilometers long. For each pair of cities (u,v), there can be more than one roads from u to v.
Bobo wants to make big news by solving the famous Hamiltonian Path problem. That is, he would like to visit all the n cities one by one so that the total distance travelled is minimized.
Formally, Bobo likes to find n distinct integers p1,p2,…,pn to minimizew(p1,p2)+w(p2,p3)+...+w(pn−1,pn)where w(x,y) is the length of road from the x-th city to the y-th city.
Input
The input contains at most 30 sets. For each set:
The first line contains 2 integers n,m (2≤n≤105,0≤m≤105).
The i-th of the following m lines contains 3 integers ai,bi,ci (1≤ai<bi≤n,1≤ci≤104).
Output
For each set, an integer denotes the minimum total distance. If there exists no plan, output -1 instead.
Sample Input
3 3 1 2 1 1 3 1 2 3 1 3 2 1 2 1 1 3 2
Sample Output
2 -1
题意：
见题目中标记的红色部分，提示说是从1 到 2,2 到3 的路径
OMG的，题目如此之水，就是需要认真审题
#include
#include
#include
using namespace std;
#define INF 0x3f3f3f
#define MANX 100010
int arr[MANX];
int main()
{
int a,b,c;
int n,m;
//freopen("in.txt","r",stdin);
while(scanf("%d%d",&n,&m)!=EOF)
{
memset(arr,INF,sizeof(arr));
for(int i=0;i