poj 2549 Sumsets

Description

Given S, a set of integers, find the largest d such that a + b + c = d where a, b, c, and d are distinct elements of S.

Input

Several S, each consisting of a line containing an integer 1 <= n <= 1000 indicating the number of elements in S, followed by the elements of S, one per line. Each element of S is a distinct integer between -536870912 and [phone] inclusive. The last line of input contains 0.

Output

For each S, a single line containing d, or a single line containing "no solution".

Sample Input

52 3 5 7 1252 16 64 256 10240

Sample Output

12no solution

Source

#include<stdio.h>#include<iostream>#include<algorithm>#include<string.h>#include<string>using namespace std;int s[1010];int main(){    int n;    while(~scanf("%d",&n)&&n)    {        int ans;        bool flag=true;        for(int i=0; i<n; i++)  scanf("%d",&s[i]);        sort(s,s+n);        int nn=unique(s,s+n)-s;        n=nn;        for(int i=n-1; i>=0; i--)        {            for(int j=0; j<n-1; j++)            {                int head=j+1,tail=n-1;                while(head<tail)                {                    int mm=s[j]+s[head]+s[tail];                    if(mm==s[i])                    {                        if(i==j||i==head||i==tail) break;                        ans=mm;                        flag=false;                        break;                    }                    else if(mm>s[i]) tail--;                    else head++;                }                if(flag==false) break;            }            if(flag==false) break;        }        if(flag==0)            printf("%d\n",ans);        else            printf("no solution\n");    }    return 0;}