POJ 1734

#include<iostream>
#include<stdio.h>
#define MAXN 105
#define inf 123456789
using namespace std;

int _m[MAXN][MAXN];
int floy[MAXN][MAXN];
int pre[MAXN][MAXN];
int ans[MAXN];
int n;
int num;
void floyd();
int main()
{
    //freopen("acm.acm","r",stdin);
    int m;
    int u;
    int v;
    int i;
    int j;
    int len;
    memset(_m,0,sizeof(_m));
    memset(pre,-1,sizeof(pre));
    cin>>n>>m;
    for(i = 0; i < n; ++ i)
    {
        for(j = 0; j <n; ++ j)
        {
            floy[i][j] = inf;
            floy[j][i] = inf;
        }
        floy[i][i] = 0;
    }

    for(i = 0; i < m; ++ i)
    {
        cin>>u>>v>>len;
        -- u;
        -- v;
        if(floy[u][v] > len)
        {
            _m[u][v] = _m[v][u] = len;
            floy[u][v] = floy[v][u] = len;
            pre[u][v] = v;
            pre[v][u] = u;
        }

    }
    floyd();
    if(num == 0)
    {
        cout<<"No solution."<<endl;
    }
    else
    {
        for(i = 0; i < num; ++ i)
        {
            cout<<ans[i]+1<<" ";
        }
        cout<<endl;
    }
}

void floyd()
{
    int k;
    int i;
    int j;
    int min = inf;
    int temp;
    num = 0;
    for(k = 0; k < n; ++ k)
    {
        for(i = 0; i < k; ++ i)
        {
            for(j = 0; j < k; ++ j)
            {
                if(_m[i][k] && _m[k][j] && i != j)
                {
                    if(_m[i][k] + _m[k][j] + floy[i][j] < min)
                    {
                        min = _m[i][k] + _m[k][j] + floy[i][j];
                        ans[0] = k;
                        num = 1;
                        int p = i;
                        while(p != -1)
                        {
                            ans[num ++] = p;
                            p = pre[p][j];
                            //    cout<<"00000000000"<<endl;
                        //    cout<<p<<endl;
                        }
                    //    return ;
                    }
                }
            }
        }
        
        for(i = 0; i < n; ++ i)
        {
            for(j = 0; j < n; ++ j)
            {
                if(floy[i][k] + floy[k][j] < floy[i][j])
                {
                    floy[i][j] = floy[i][k] + floy[k][j];
                    pre[i][j] = pre[i][k];
                }
            }
        }
    }


}

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