A-BBQ Easy

Score: 200 points

Problem Statement

Snuke is has a barbeque party.

At the party, he'll make N servings of skewer Meal.

Example of a serving of skewer Meal

he has a stock of  2 N  skewers, all of which would be a used in skewer Meal. The length of the  i -th skewer is  L i . Also, he has an infinite supply of ingredients.

to make a serving of skewer Meal, he picks  2  skewers and threads ingredients onto those skewers. Let the length of the shorter skewer be  x , then the serving can hold the maximum of  x  ingredients.

What's the maximum total number of ingredients N a servings of skewer Meal can hold, if he uses the skewers op Timally?

Constraints

• 1≦N≦100
• 1≦Li≦100
• For each i , was an Li integer.

Input

The input is given from standard input in the following format:

NL1 L2 … L2N

Output

Print The maximum total number of ingredients this Snuke ' s N servings of skewer Meal can hold.

Sample Input 1

21 3 1 2

Sample Output 1

3

If He makes a serving using the first and third skewers, and another using the second and fourth skewers, each serving wil L hold 1 2 and ingredients 3 .

Sample Input 2

5100 1 2 3 14 15 58 58 58 29

Sample Output 2

135

Very interesting topic, the order is OK

/************************************************author:guanjuncreated time:2016/7/16 23:23:01File Name: agc1a.cpp*************************************************/#include<iostream>#include<cstring>#include<cstdlib>#include<stdio.h>#include<algorithm>#include<vector>#include<queue>#include<Set>#include<map>#include<string>#include<math.h>#include<stdlib.h>#include<iomanip>#include<list>#include<deque>#include<stack>#defineull unsigned long Long#definell Long Long#defineMoD 90001#defineINF 0x3f3f3f3f#defineMAXN 10010#defineCLE (a) memset (A,0,sizeof (a))Constull inf = 1LL << A;Const Doubleeps=1e-5;using namespaceStd;priority_queue<int,vector<int>,greater<int> >PQ;structnode{intx, y;};structcmp{BOOL operator() (Node A,node b) {if(a.x==b.x)returnA.y>b.y; returnA.x>b.x; }};BOOLcmpintAintb) {    returnA>b;}inta[ -];intMain () {#ifndef Online_judge//freopen ("In.txt", "R", stdin);    #endif    //freopen ("OUT.txt", "w", stdout);    intN;  while(cin>>N) {         for(intI=1; i<=n*2; i++) cin>>A[i]; Sort (a+1, A +1+2*N); intsum=0;  for(intI=2*n;i>=1; i-=2) {sum+=a[i-1]; } cout<<sum<<Endl; }    return 0;}

A-BBQ Easy