KMIT_NGIT_Fair.cpp

// Keshav Memorial Group of Institutions, planning to conduct Mock-Interviews 
// for Finishing School Students in KMIT and NGIT Colleges.

// There are N students to participate in the interview,where N is an even number. 
// You will be given an array of tariffs as fare[], 
// where fare[a]=[fareToReachKmit-a, fareToReachNgit-a],
//  - fareToReachKmit-a indicates cab fare for Student-a to reach KMIT campus.
//  - fareToReachNgit-a indicates cab fare for Student-a to reach NGIT campus.

// Keshav Memorial Management decided to refund the cab fare to every student. 

// Your task is to help the management to find the minimum total fare to be paid 
// by all the students to attend the interviews in KMIT and NGIT, such that both 
// the colleges should conduct interviews for equal number of students.

// Input Format:
// -------------
// Line-1: An integer N, number of students.
// Next N lines: Two space separated integers, fares to reach KMIT and NGIT. 

// Output Format:
// --------------
// Print an integer, minimum fare paid by N students(to be refunded).


// Sample Input-1:
// ---------------
// 6
// 10 75
// 35 120
// 105 45
// 80 110
// 125 85
// 65 100

// Sample Output-1:
// ----------------
// 350

// Explanation:
// ------------
// Student-1 attended interview in KMIT with fare - 10.
// Student-2 attended interview in KMIT with fare - 35.
// Student-3 attended interview in NGIT with fare - 45.
// Student-4 attended interview in NGIT with fare - 110.
// Student-5 attended interview in NGIT with fare - 85.
// Student-6 attended interview in KMIT with fare - 65.
// 3 students attended in KMIT and 3 students attended in NGIT.
// So, the total minimum fare is to be refunded 350.


// Sample Input-2:
// ---------------
// 6
// 159 635
// 495 67
// 784 571
// 221 243
// 783 134
// 524 476

// Sample Output-2:
// ----------------
// 1676



#include<bits/stdc++.h>
using namespace std;
int main(){
    int n;
    cin>>n;
    vector<vector<int>> nums(n,vector<int>(2,0));
    for(int i=0;i<n;i++){
        for(int j=0;j<2;j++){
            cin>>nums[i][j];
        }
    }
    sort(nums.begin(),nums.end(),[&](vector<int> a,vector<int> b){
        if(a[0]-a[1]<b[0]-b[1]){
            return true;
        }
        else{
            return false;
        }
    });
    int res=0;
    for(int i=0;i<nums.size();i++){
        if(i<n/2){
            res=res+nums[i][0];
        }
        else{
            res=res+nums[i][1];
        }
    }
    cout<<res;
}