POJ 2230

#include<iostream>using namespace std;int u[100000+1];int v[100000+1];int next[100000+1];int pnt[10000+1];int visit[100000+1];int n,m,e;void add(int a, int b){ //建造邻接表u[++e] = a, v[e] = b;next[e] = pnt[a]; pnt[a] = e;}void dfs(int root){//是根据图的边来建造图，visit是确认边是否经边一次；int i;for(i = pnt[root]; i!=0; i = next[i]){if(!visit[i]){visit[i] = true;dfs(v[i]);}}printf("%d\n",root);}int main(){scanf("%d %d",&n,&m);int a,b;for(int i = 0; i < m; ++i){scanf("%d %d",&a,&b);add(a, b);add(b, a);}dfs(1);}