【ACM】吝啬的国度 - DFS (图)

 
#include <iostream>
#include <string>
#include <cstdio>
#include <cmath>
#include <vector>

using namespace std;
int *a;
vector<int> *v;
int m;

void DFS(int cur){

    for (int i = 0 ; i < v[cur].size() ;i++)
    {
        if (a[v[cur][i]]!=0)
        {
            continue;
        }
        a[v[cur][i]] = cur;
        DFS(v[cur][i]);
    }
    
}

int main(){

    int n;
    cin>>n;
    while (n--)
    {
        int cur;
        cin>>m>>cur;

        a = new int[m+1];
        for (int z = 0; z < m+1 ; z++)
        {
            a[z] = 0;
        }
        v = new vector<int>[m+1];
        int x,y;
        for (int i = 1 ; i < m ; i++)
        {
            cin>>x>>y;
            v[x].push_back(y);
            v[y].push_back(x);
        }
        
        DFS(cur);
        int k;
        for (k = 0; k < m-1 ;k++)
        {
            if (k+1==cur)
            {
                cout<<"-1 ";
            }else
            {
                cout<<a[k+1]<<" ";
            }
        }
        if (k+1==cur)
        {
            cout<<"-1"<<endl;
        }
        else
        {
            cout<<a[k+1]<<endl;
        }
    }

    return 0;
}