Codeforces Round 192 B. Road Construction

# include <stdio.h># include <string.h>int main (){int n,i,m,mark,b,c;int a[1005];memset(a,0,sizeof(a));    scanf("%d %d",&n,&m);for(i=1;i<=m;i++){scanf("%d %d",&b,&c);a[b]=1;a[c]=1;}for(i=1;i<=n;i++)if(a[i]==0)mark=i;printf("%d\n",n-1);for(i=1;i<=n;i++){if(i==mark)continue;elseprintf("%d %d\n",i,mark);}return  0;}

图论的第一题  纪念一下     主要找的是星状图