CF C - Table Decorations

C - Table Decorations
Time Limit:1000MS Memory Limit:262144KB 64bit IO Format:%I64d & %I64u
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Status

Practice

CodeForces 478C
Description
You have r red, g green and b blue balloons. To decorate a single table for the banquet you need exactly three balloons. Three balloons attached to some table shouldn’t have the same color. What maximum number t of tables can be decorated if we know number of balloons of each color?

Your task is to write a program that for given values r, g and b will find the maximum number t of tables, that can be decorated in the required manner.

Input
The single line contains three integers r, g and b (0?≤?r,?g,?b?≤?2·109) — the number of red, green and blue baloons respectively. The numbers are separated by exactly one space.

Output
Print a single integer t — the maximum number of tables that can be decorated in the required manner.

Sample Input
Input
5 4 3
Output
4
Input
1 1 1
Output
1
Input
2 3 3
Output
2
思路：a[1],a[2],a[3]从小到大排序，如果(a[1]+a[2])*2<=a[3]那么最大值就是a[1]+a[2];
否则： 最大值就是三个数的和整除3（可以认为每张桌子的装饰都是 由最大值贡献2，次大值贡献1）

#include <iostream>
#include <stdio.h>
#include <string>
#include <string.h>
#include <algorithm>
using namespace std;
typedef long long ll;
ll a[5];

int main()
{
    while(cin>>a[1]>>a[2]>>a[3])
    {
      ll sum=0;
      sort(a+1,a+4);
      if((a[1]+a[2])*2<=a[3])sum=a[1]+a[2];
      else sum=(a[1]+a[2]+a[3])/3;
      printf("%I64d\n",sum);
    }
    return 0;
}