map,  用实力值当做关键字

#include <iostream>
#include <memory.h>
#include <map>
#include <stdio.h>
#define IN (1<<28)
using namespace std;
int N;
map <int,int> record;
int main()
{
    cin >> N;
    record[1000000000] = 1;
    for( int i = 1; i <= N; i++ )
    {
        int id,value;
        scanf("%d %d", &id, &value);
        record[value] = id;
        map<int,int>::iterator p = record.find(value);
        map<int,int>::iterator j;
        map<int,int>::iterator k;
        if( p != record.end() )
        {
             if( p == record.begin() )
             {
                 j = p;
                 j++;
                 cout << p->second << ' ' << j->second << endl;
             }
             else
             {
                 j = p;
                 j++;
                 k = p;
                 k--;
                 int up = j->first - p->first;
                 int low = p->first - k->first;
                 if( low <= up )
                 {
                     cout << p->second << ' ' << k->second << endl;
                 }
                 else
                 {
                     cout << p->second << ' ' << j->second << endl;
                 }
             }
        }
        else
            break;
    }
    return 0;
}