C :

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
int number[1003];
int word[100000];
void make(int head,int ptail,int mid)
{
    int i,j,k;
    int *x=(int *)malloc((ptail-head+1)*sizeof(int));
    for (i=head,j=mid+1,k=0;i<=mid&&j<=ptail;k++)
    {
        if (number[i]<number[j])
        x[k]=number[i++];
        else
        x[k]=number[j++];
    }
    while(i<=mid)
    x[k++]=number[i++];
    while(j<=ptail)
    x[k++]=number[j++];
    for (i=head,j=0;j<k;i++,j++)
    number[i]=x[j];
    free(x);
}
void sort(int head,int ptail)
{
    if (head>=ptail) return;
    int mid=(head+ptail)/2;
    sort(head,mid);
    sort(mid+1,ptail);
    make(head,ptail,mid);
}
int main(void)
{//freopen("love.txt","r",stdin);
    int n,i,j;
    while(scanf("%d",&n)!=EOF)
    {
        if (n==0) break;
        memset(number,0,sizeof(number)); memset(word,0,sizeof(word));
        scanf("%d",&number[0]);
        for (i=1;i<n;i++)
        {
            scanf("%d",&number[i]);
            for (j=i-1;j>=0;j--)
            {
                int sum=number[i]+number[j];
                word[sum]=1;
            }
        }
        sort(0,n-1);
        int flag=0;
        for (i=n-1;i>=0;i--)
        {
            for (j=i-1;j>=0;j--)
            {
                int sum=number[i]-number[j];
                if (word[sum]!=0)
                {
                    flag=1;
                    printf("%d\n",number[i]);
                    break;
                }
            }
            if (flag==1) break;
        }
        if (flag==0)
        printf("no solution\n");
    }
    return 0;
}

C++ :

#include<cstdio>
#include<algorithm>
using namespace std;

int bs(int a[],int l,int r,int x)
{
	int m;
	while(l<r)
	{
		m=(l+r)>>1;
		if(a[m]==x)
			return m;
		if(a[m]<x)
			l=m+1;
		else
			r=m;
	}
	return -1;
}

int main()
{
	int n,a[1000],i,j,k,bet,p,flag,ans;
	while(scanf("%d",&n)!=EOF,n)
	{
		for(i=0;i<n;i++)
			scanf("%d",&a[i]);
		sort(a,a+n);
		for(flag=0,i=n-1;i>=0;i--)
		{
			for(j=0;j<i;j++)
			{
				for(k=j+1;k<n;k++)
				{
					bet=a[i]-a[j]-a[k];
					p=bs(a,k+1,n,bet);
					if(p!=-1&&p!=i)
					{
						ans=i;
						flag=1;
						break;
					}
				}
				if(flag)
					break;
			}
			if(flag)
				break;
		}
		if(flag)
			printf("%d\n",a[ans]);
		else
			puts("no solution");
	}
	return 0;
}

Java :

import java.util.*;
public class Main{
    public static void main(String[] args){
        Scanner in = new Scanner(System.in);
        while(in.hasNextInt()){
            int n = in.nextInt();
            if(n==0)
            break;
            if(n==0)
            break;
            int[] x = new int[n];
            for(int i=0;i<n;i++){
                x[i] = in.nextInt(); 
            }
            Arrays.sort(x);
            boolean a = false;
            for(int i=n-1;i>=3;i--){
                for(int j=0;j<i;j++){
                    for(int k=0;k<i;k++){
                        if(k==j)
                        continue;
                        for(int m=0;m<i;m++){
                            if(m==j||m==k)
                            continue;
                            if(x[i]==x[j]+x[k]+x[m]){
                                a = true;
                                System.out.println(x[i]);
                                break;
                            }
                        }
                        if(a)
                        break;
                    }
                    if(a)
                    break;
                }
                if(a)
                break;
            }
            if(!a){
                System.out.println("no solution");
            }
        }
    }
}