Go: ///
// File:  0529.go
// Author: ymiyamoto
//
// Created on Wed Feb 28 20:39:28 2018
//
package main

import (
	"fmt"
	"sort"
)

func max(n, m int64) int64 {
	if n < m {
		return m
	} else {
		return n
	}
}

func main() {
	for {
		var N int
		var M int64
		fmt.Scan(&N, &M)
		if N == 0 && M == 0 {
			break
		}

		arr := make([]int64, N+1)
		for i := 1; i <= N; i++ {
			fmt.Scan(&arr[i])
		}
		sort.Slice(arr, func(i, j int) bool { return arr[i] < arr[j] })

		sums := make([]int64, len(arr)*len(arr))
		for i := 0; i < len(arr); i++ {
			for j := 0; j < len(arr); j++ {
				sums[i*len(arr)+j] = arr[i] + arr[j]
			}
		}

		sort.Slice(sums, func(i, j int) bool { return sums[i] < sums[j] })

		var m int64 = 0
		for i := 0; i < len(sums); i++ {
			rem := M - sums[i]
			if rem >= 0 {
				index := sort.Search(len(sums), func(i int) bool { return sums[i] > rem }) - 1
				if index >= 0 {
					m = max(m, sums[i]+sums[index])
				}
			}
		}
		fmt.Println(m)
	}
}

C++: 
#include<stdio.h>
#include<stdlib.h>
#include<math.h>

int main()
{
	int ans[4];
	int temp;
	double energy,energy_min,energy_now;
	int M, N;
	int* p;
	int i, j;
	double T=100;
	int ret;
	while (1) {
		scanf("%d%d", &N, &M);
		p = (int*)malloc((N+1) * sizeof(int));
		for (i = 0; i < N; i++) {
			scanf("%d", &p[i]);
		}
		p[N] = 0;
		if (N == M && N == 0) {
			break;
		}
		energy_min = pow(10, 300);
		for (j = 0; j < 4; j++) {
			ans[j] = p[(int)((double)(rand() + 1) / (RAND_MAX + 2)*(N+1))];
		}
		
		for (T = 1000000; T > 100; T--) {
			for (j = 0; j < 4; j++) {
				temp = p[(int)((double)(rand() + 1) / (RAND_MAX + 2)*(N+1))];
				for (j = 0; j < 4; j++) {
					ret = ans[0] + ans[1] + ans[2] + ans[3];
					ret += temp - ans[j];
					energy = M - ret;
					if (M < ret)energy += 100000000;

					if (energy < energy_min) {
						energy_min = energy;
						ans[j] = temp;
					}
					else if ((double)(rand() + 1) / (RAND_MAX + 2) < exp((energy_min - energy) / T*10)) {
						energy_min = energy;
						ans[j] = temp;
					}
				}

			}
		}
		ret=ans[0]+ +ans[1] + ans[2] + ans[3];
		printf("%d\n", ret);
	}
    return 0;
}

C++: #include <bits/stdc++.h>
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n)  for(int i=0;i<(n);++i)
#define REPr(i,n) for(int i=(n)-1;i>=0; --i)
#define FORq(i, m, n) for(int i = (m);i <= (n);++i)
#define SCD(n) scanf("%d",&n)
#define SCD2(m,n) scanf("%d%d",&m,&n)
#define SCD3(m,n,k) scanf("%d%d%d",&m,&n,&k)
#define SCLLD(n) scanf("%lld",&n)
#define SCLLD2(m,n) scanf("%lld%lld",&m,&n)
#define SCLLD3(m,n,k) scanf("%lld%lld%lld",&m,&n,&k)
#define PB push_back
#define MP make_pair
#define ARSCD(A,N) REP(i,N){SCD(A[i]);}
#define ARSCD1(A,N) FORq(i,1,N){SCD(A[i]);}
#define VSCD(v,N) REP(i,N){int x; SCD(x); v.PB(x);}
#define VSCLLD(v,N) REP(i,N){long long x; SCLLD(x); v.PB(x);}
#define PRINTD(n) printf("%d\n",n)
#define PRINTLLD(n) printf("%lld\n",n)
#define DEBUG printf("%s\n","debug")
#define fst first
#define snd second
#define SIN(x,S) (S.count(x) != 0)
using namespace std;
typedef pair<int,int> PII;
typedef vector<int> VI;
typedef vector < VI > VVI;
typedef vector<long long> VL;
typedef long long ll;
typedef long long integer;
////////////////////////////////////////////////////////////////////
int main(){
	while(true){
		int N; SCD(N);
		int M; SCD(M);
		if ((N==0) and (M==0)) break;

		vector<int> P;
		P.PB(0);
		VSCD(P,N);

		vector<int> Ptwo;

		REP(i,N+1){
			REP(j,N+1){
				Ptwo.PB(P[i] + P[j]);
				//printf("P[%d] + P[%d] = %d\n",i,j,P[i]+P[j]);
			}
		}

		sort(Ptwo.begin(),Ptwo.end());

		int ans = 0;

		REP(i,(N+1)*(N+1)){
			int f,s;
			f = Ptwo[i];
			auto it = lower_bound(Ptwo.begin(),Ptwo.end(),M-f);
			int sind = it - Ptwo.begin();
			//printf("f = %d,sind = %d\n",f,sind);
			if (sind > (N+1)*(N+1)-1) continue;
			if (Ptwo[sind] != M-f) sind--;
			if (sind < 0) continue;
			s = Ptwo[sind];
			ans = max(ans,f+s);
		}
		PRINTD(ans);
	}
	return 0;
}

C++: //include----------------------------------------------------------------------------------------------------------------------
#include <bits/stdc++.h>
//using namespace--------------------------------------------------------------------------------------------------------------
using namespace std;

//define-----------------------------------------------------------------------------------------------------------------------
#define rep(i, n) for(int i = 0; i < (int)n; i++)
#define FOR(i, s, n) for(int i = s; i < (int)n; i++)
#define per(i, n) for(int i = n; i >= 0; i--)
#define ROF(i, s, n) for(int i = s; i >= (int)n; i--)
#define FORIT(i, A) for (auto i : A)
#define PRINT(x) cout << (x) << "\n"
#define ALL(a) (a).begin(),(a).end()
#define RALL(a) (a).rbegin(), (a).rend()
#define MP make_pair
#define EACH(i, n) for (__typeof((n).begin()) i = (n).begin(); i != (n).end(); ++i)
#define SZ(a) int((a).size())
#define EXIST(s,e) ((s).find(e)!=(s).end())
#define SORT(c) sort((c).begin(),(c).end())
#define CLR(a) memset((a), 0 ,sizeof(a))
#define dump(x) cout << #x << " = " << (x) << "\n";
#define debug(x) cout << #x << " = " << (x) << " (L" << __LINE__ << ")" << " " << __FILE__ << "\n";
#define sq(n) (n) * (n)

//typedef----------------------------------------------------------------------------------------------------------------------
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<string> VS;
typedef pair<int, int> PII;
typedef long long LL;
typedef vector<LL> VLL;
typedef vector<VLL> VVLL;
typedef unsigned int uint;
typedef unsigned long long ull;
typedef priority_queue<int> maxpq;
typedef priority_queue< int, vector<int>, greater<int> > minpq;
//const------------------------------------------------------------------------------------------------------------------------
static const double EPS = 1e-10;
static const double PI = acos( -1.0 );
static const int mod = 1000000007;
static const int INF = 1 << 25;
static const LL LL_INF = 1152921504606846976;
//global-----------------------------------------------------------------------------------------------------------------------
int n, m, ans = 0;
VI a;
//#define DEBUG
//function-------------------------------------------------------------------------------------------------------------------
int main() {
	while ( scanf( "%d %d", &n, &m ) && n && m ) {
		a.resize( n );
		rep( i, n ) {
			scanf( "%d", &a[ i ] );
		}
		ans = 0;
		sort( a.rbegin(), a.rend() );
		rep( i, n ) {
			while ( ans <= m ) {
				ans += a[ i ];
			}
			ans -= a[ i ];
		}
		printf( "%d\n", ans );
	}
	return 0;
}

C++: #include <cstdio>
#include <algorithm>
int a[1001],b[510001],*p;main(){
	int n,m,i,j,k,r;
	for(;scanf("%d%d",&n,&m)>1&&n;printf("%d\n",r)){
		for(i=1;i<=n;i++)scanf("%d",a+i);
		for(k=i=0;i<=n;i++)for(j=i;j<=n;j++)b[k++]=a[i]+a[j];
		std::sort(b,b+k);
		for(r=i=0;i<k;i++){
			p=std::upper_bound(b,b+k,m-b[i]);
			if(p>b&&r<b[i]+*(p-1))r=b[i]+*(p-1);
		}
	}
}

C++: #include <bits/stdc++.h>
#define PB push_back
#define MP make_pair
#define REP(i,n) for (int i=0;i<(n);i++)
#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define ALL(a) (a).begin(),(a).end()
#define MOD 100000
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> P;
const int INF=1e9;
int main(){
      int n,m,a[1001];
      while(cin>>n>>m&&(n||m)){
            int ans=0;
            vector<int>V;
            a[0]=0;
            REP(i,n)cin>>a[i+1];
            n++;
            REP(i,n)REP(j,n)V.PB(a[i]+a[j]);
            sort(ALL(V));
            REP(i,n)REP(j,n){
                  int b=a[i]+a[j];
                  if(b>m)continue;
                  ans=max(ans,*(lower_bound(V.begin(),V.end(),m-b)-1)+b);
            }
            cout<<ans<<endl;
      }
      return 0;
}