DGOLD - Chia vàng
Tác giả: hieult
Ngôn ngữ: C++
#include <set>
#include <map>
#include <list>
#include <cmath>
#include <queue>
#include <stack>
#include <cstdio>
#include <string>
#include <vector>
#include <cstdlib>
#include <cstring>
#include <sstream>
#include <iomanip>
#include <iostream>
#include <algorithm>
#include <ctime>
#include <deque>
#include <bitset>
#include <cctype>
#include <utility>
#include <cassert>
using namespace std;
typedef long long ll;
typedef double ld;
typedef unsigned int ui;
typedef unsigned long long ull;
#define Rep(i,n) for(int i = 0; i < (n); ++i)
#define Repd(i,n) for(int i = (n)-1; i >= 0; --i)
#define For(i,a,b) for(int i = (a); i <= (b); ++i)
#define Ford(i,a,b) for(int i = (a); i >= (b); --i)
#define Fit(i,v) for(__typeof((v).begin()) i = (v).begin(); i != (v).end(); ++i)
//#define Fitd(i,v) for(__typeof((v).rbegin()) i = (v).rbegin(); i != (v).rend(); ++i)
#define mp make_pair
#define pb push_back
#define fi first
#define se second
#define sz(a) ((int)(a).size())
#define all(a) (a).begin(), (a).end()
#define ms(a,x) memset(a, x, sizeof(a))
template<class F, class T> T convert(F a, int p = -1) { stringstream ss; if (p >= 0) ss << fixed << setprecision(p); ss << a; T r; ss >> r; return r; }
template<class T> T gcd(T a, T b) { T r; while (b != 0) { r = a % b; a = b; b = r; } return a; }
template<class T> T lcm(T a, T b) { return a / gcd(a, b) * b; }
template<class T> T sqr(T x) { return x * x; }
template<class T> T cube(T x) { return x * x * x; }
template<class T> int getbit(T s, int i) { return (s >> i) & 1; }
template<class T> T onbit(T s, int i) { return s | (T(1) << i); }
template<class T> T offbit(T s, int i) { return s & (~(T(1) << i)); }
template<class T> int cntbit(T s) { return s == 0 ? 0 : cntbit(s >> 1) + (s & 1); }
const int bfsz = 1 << 16;
char bf[bfsz + 5];
int rsz = 0;
int ptr = 0;
char gc() {
if (rsz <= 0) {
ptr = 0;
rsz = (int) fread(bf, 1, bfsz, stdin);
if (rsz <= 0)
return EOF;
}
--rsz;
return bf[ptr++];
}
void ga(char &c) {
c = EOF;
while (!isalpha(c))
c = gc();
}
int gs(char s[]) {
int l = 0;
char c = gc();
while (isspace(c))
c = gc();
while (c != EOF && !isspace(c)) {
s[l++] = c;
c = gc();
}
s[l] = '\0';
return l;
}
template<class T> bool gi(T &v) {
v = 0;
char c = gc();
while (c != EOF && c != '-' && !isdigit(c))
c = gc();
if (c == EOF)
return false;
bool neg = c == '-';
if (neg)
c = gc();
while (isdigit(c)) {
v = v * 10 + c - '0';
c = gc();
}
if (neg)
v = -v;
return true;
}
typedef pair<int, int> II;
const ld PI = acos(-1.0);
const ld eps = 1e-9;
const int dr[] = {0, +1, 0, -1};
const int dc[] = {+1, 0, -1, 0};
const int inf = (int)1e9 + 5;
const ll linf = (ll)1e16 + 5;
const ll mod = (ll)1e9 + 7;
int n, a[25], b[25], m, Ma[(1 << 13) + 5], Mb[(1 << 13) + 5];
vector<II> Vt, V;
vector<int> V1, V2;
bool comp(const II &P0,const II &P1){
if(P0.fi == P1.fi) return P0.se > P1.se;
return P0.fi < P1.fi;
}
int main()
{
// freopen("in.txt", "r", stdin);
cin >> n;
Rep(i, n) cin >> a[i];
m = n - n / 2;
n = n / 2;
Rep(i, m) b[i] = a[n + i];
int res = 0, mask2, T1, T2, T;
Rep(mask, (1 << n)){
Ma[mask] = 0;
Rep(i, n) Ma[mask] += getbit(mask, i) * a[i];
}
Rep(mask, (1 << m)){
Mb[mask] = 0;
Rep(i, m) Mb[mask] += getbit(mask, i) * b[i];
}
Rep(mask, (1 << n)){
for(int mask1 = mask; mask1 > 0; mask1 = mask & (mask1 - 1)){
mask2 = mask ^ mask1;
T1 = Ma[mask1]; T2 = Ma[mask2];
if(T1 == T2) res = max(res, T1 + T2);
T = abs(T1 - T2);
Vt.pb(mp(T, T1 + T2));
}
}
sort(all(Vt), comp);
V.pb(Vt[0]);
for(int i = 1; i < sz(Vt); i++){
if(Vt[i].fi > Vt[i - 1].fi) V.pb(Vt[i]);
}
int size = sz(V), t;
Rep(i, size){
V1.pb(V[i].fi);
V2.pb(V[i].se);
}
Rep(mask, (1 << m)){
for(int mask1 = mask; mask1 > 0; mask1 = mask & (mask1 - 1)){
mask2 = mask ^ mask1;
T1 = Mb[mask1]; T2 = Mb[mask2];
if(T1 == T2) res = max(res, T1 + T2);
T = abs(T1 - T2);
t = lower_bound(all(V1), T) - V1.begin();
if(t < size && V1[t] == T){
res = max(res, V2[t] + T1 + T2);
}
}
}
cout << res / 2 << endl;
// cout << clock() << endl;
return 0;
}