360 2015校园招聘 第二题

#include <iostream>
#include <string>
#include <vector>
#include <set>
#include <algorithm>
using namespace std;
typedef struct node{
    int node1;
    int node2;
} node;
bool comp1(node x,node y){
    if(x.node1<y.node1)
        return true;
    else if(x.node1>y.node1)
        return false;
    else{
        if(x.node2<y.node2)
            return true;
        else
            return false;
    }
}
bool comp2(node x,node y){
    if(x.node1<y.node1)
        return false;
    else if(x.node1>y.node1)
        return true;
    else{
        if(x.node2<y.node2)
            return false;
        else
            return true;
    }
}
int main(){
    while(1){
        int N,M;
        cin>>N;
        cin>>M;
        if(N==0&&M==0)
            break;
        set<int> people;
        vector<node> vct;
        for(int i=0;i<M;++i){
            int p1,p2;
            cin>>p1>>p2;
            node nd;
            if(p1<p2){
                nd.node1=p1;
                nd.node2=p2;
            }
            else{
                nd.node1=p2;
                nd.node2=p1;
            }
            vct.push_back(nd);
        }
        people.insert(1);
        sort(vct.begin(),vct.end(),comp1);
        for(int i=0;i<M;++i){
            if(people.find(vct[i].node1)!=people.end())
                people.insert(vct[i].node2);
        }
        for(int i=M-1;i>=0;--i){
            if(people.find(vct[i].node1)!=people.end())
                people.insert(vct[i].node2);
        }
        for(int i=0;i<M;++i){
            if(people.find(vct[i].node2)!=people.end())
                people.insert(vct[i].node1);
        }
        for(int i=M-1;i>=0;--i){
            if(people.find(vct[i].node2)!=people.end())
                people.insert(vct[i].node1);
        }

        sort(vct.begin(),vct.end(),comp2);
        for(int i=0;i<M;++i){
            if(people.find(vct[i].node1)!=people.end())
                people.insert(vct[i].node2);
        }
        for(int i=M-1;i>=0;--i){
            if(people.find(vct[i].node1)!=people.end())
                people.insert(vct[i].node2);
        }
        for(int i=0;i<M;++i){
            if(people.find(vct[i].node2)!=people.end())
                people.insert(vct[i].node1);
        }
        for(int i=M-1;i>=0;--i){
            if(people.find(vct[i].node2)!=people.end())
                people.insert(vct[i].node1);
        }
        cout<<people.size()-1<<endl;
    }
    return 0;
}