Submission #3437198

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Source Code Expand

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

typedef long long ll;
typedef unsigned long long ull;
typedef pair<ll, ll> P;

#define fi first
#define se second
#define repl(i,a,b) for(ll i=(ll)(a);i<(ll)(b);i++)
#define rep(i,n) repl(i,0,n)
#define all(x) (x).begin(),(x).end()
#define dbg(x) cout<<#x"="<<x<<endl
#define mmax(x,y) (x>y?x:y)
#define mmin(x,y) (x<y?x:y)
#define maxch(x,y) x=mmax(x,y)
#define minch(x,y) x=mmin(x,y)
#define uni(x) x.erase(unique(all(x)),x.end())
#define exist(x,y) (find(all(x),y)!=x.end())
#define bcnt __builtin_popcountll

#define INF 1e16
#define mod 1000000007

ll N,K;
ll A[20];
ll dp[1<<18];

int main(){
  cin.tie(0);
  ios::sync_with_stdio(false);

  cin>>N>>K;
  rep(i,N)cin>>A[i];
  dp[0]=1;
  rep(S,(1<<N)-1){
    ll k=0;
    while((S>>k)&1)k++;
    dp[S|(1<<k)]+=dp[S];

    repl(i,k+1,N){
      if((S>>i)&1)continue;
      if(A[i]+A[k]>K*2)continue;
      dp[S|(1<<i)|(1<<k)]+=dp[S];
    }

    repl(i,k+1,N)repl(j,i+1,N){
      if((S>>i)&1)continue;
      if((S>>j)&1)continue;
      if(A[i]+A[j]+A[k]>K*3)continue;
      dp[S|(1<<i)|(1<<j)|(1<<k)]+=dp[S];
    }
  }
  cout<<dp[(1<<N)-1]<<endl;

  return 0;
}

Submission Info

Judge Result