B. Qualifying Contest

题目链接http://codeforces.com/contest/659/problem/B

Description

Very soon Berland will hold a School Team Programming Olympiad. From each of the m Berland regions a team of two people is invited to participate in the olympiad. The qualifying contest to form teams was held and it was attended by n Berland students. There were at least two schoolboys participating from each of the m regions of Berland. The result of each of the participants of the qualifying competition is an integer score from 0 to 800 inclusive.

The team of each region is formed from two such members of the qualifying competition of the region, that none of them can be replaced by a schoolboy of the same region, not included in the team and who received a greater number of points. There may be a situation where a team of some region can not be formed uniquely, that is, there is more than one school team that meets the properties described above. In this case, the region needs to undertake an additional contest. The two teams in the region are considered to be different if there is at least one schoolboy who is included in one team and is not included in the other team. It is guaranteed that for each region at least two its representatives participated in the qualifying contest.

Your task is, given the results of the qualifying competition, to identify the team from each region, or to announce that in this region its formation requires additional contests.

Input

The first line of the input contains two integers n and m (2 ≤ n ≤ 100 000, 1 ≤ m ≤ 10 000, n ≥ 2m) — the number of participants of the qualifying contest and the number of regions in Berland.

Next n lines contain the description of the participants of the qualifying contest in the following format: Surname (a string of length from 1 to 10 characters and consisting of large and small English letters), region number (integer from 1 to m) and the number of points scored by the participant (integer from 0 to 800, inclusive).

It is guaranteed that all surnames of all the participants are distinct and at least two people participated from each of the m regions. The surnames that only differ in letter cases, should be considered distinct.

Output

Print m lines. On the i-th line print the team of the i-th region — the surnames of the two team members in an arbitrary order, or a single character "?" (without the quotes) if you need to spend further qualifying contests in the region.

Sample Input

5 2

Ivanov 1 763

Andreev 2 800

Petrov 1 595

Sidorov 1 790

Semenov 2 503

Sample Output

Sidorov Ivanov

Andreev Semenov

题意：

给你n个人m只队伍。问能否每对确定得分最高的两个人。能则输出人名，不能则输出“？”。

题解：

只需开m个数组，鉴于太大，可使用vector。再对每个队伍排序。如只有两个人，输出这两个人。如果超过两个人如果第二个人和第三个人得分相同则输出“？”，否则输出前两个人人名。

代码：

#include<bits/stdc++.h>

using namespace std;

struct node

{

    char name[15];

    int dui;

    int fen;

};

bool cmp(node s1,node s2)

{

    return s1.fen > s2.fen;

}

vector <node> s[100100];

int main()

{

    int n,m;

    scanf("%d%d",&n,&m);

    node temp;

    for (int i = 1; i <= n; i++)

    {

        scanf("%s %d %d",temp.name,&temp.dui,&temp.fen);

        s[temp.dui].push_back(temp);

    }

    for (int i = 1; i <= m; i++)

    {

        sort(s[i].begin(),s[i].end(),cmp);

        if (s[i].size()==2)

            printf("%s %s\n",s[i][0].name,s[i][1].name);

        else {

            if (s[i][1].fen == s[i][2].fen)

                printf("?\n");

            else

                printf("%s %s\n",s[i][0].name,s[i][1].name);

        }

    }

}