Submission #1812462

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Source Code Expand

#include<bits/stdc++.h>
using namespace std;
#define rep(i,a,b) for(int i=(a);i<=(b);i++)
#define re(i,a,b) for(int i=(a);i<(b);i++)
#define repd(i,a,b) for(int i=(a);i>=(b);i--)
#define per(i,a,b) for(int i=(a);i>=(b);i--)
#define Rep(i,a,b) for(int i=(a);i<(b);i++)
#define fi first
#define se second
#define clr(a) memset(a,0,sizeof(a));
#define il inline
#define sz(a) ((int)o.size())
#define run(x) for(int k=head[x];k;k=e[k].ne)
#define v e[k].t
#define all(a) o.begin(),o.end()
#define pb push_back 
#define w1 first
#define w2 second
#define adm(a,b,c) {a=a+b;if(a>=c)a-=c;else if(a<0)a+=c;}
typedef double db;
typedef long long ll;typedef long double ld;typedef unsigned long long ull;
typedef pair<int,int> pa;
const int N=100+5,INF=1e9,mod=1e9+7;
const ll linf=1e18;const double eps=1e-8,pi=acos(-1);
il int gmin(int &a,int b){if(a>b)a=b;}il ll gmin(ll &a,ll b){if(a>b)a=b;}il int gmax(int &a,int b){if(a<b)a=b;}il ll gmax(ll &a,ll b){if(a<b)a=b;}
il void read(ll&x){ll f=1,t=0;char ch=getchar();while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}while(ch>='0'&&ch<='9'){t=t*10+ch-'0';ch=getchar();}x=t*f;}il ll read(ll&x,ll&y){read(x);read(y);}
il void read(int&x){int f=1,t=0;char ch=getchar();while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}while(ch>='0'&&ch<='9'){t=t*10+ch-'0';ch=getchar();}x=t*f;}il int read(int&x,int&y){read(x);read(y);}
il void read(int&a,int&b,int&c){read(a);read(b);read(c);}il void read(ll&a,ll&b,ll&c){read(a);read(b);read(c);}
il int read(){int x;read(x);return x;}
il void judge(){
	freopen("dato.in","r",stdin);
	freopen("dato.out","w",stdout);
}
int n,a[N],f[N][N][N];
void ad(int&x,int y){x+=y;x%=mod;}
int main(){
	read(n);rep(i,1,n+n-1)read(a[i]);
	sort(a+1,a+1+2*n-1);
	f[n][1][1]=1;
	repd(i,n,2)
	rep(j,1,2*(n-i)+1)rep(k,1,2*(n-i)+1)if(f[i][j][k]){
		int nj=j+(a[i]!=a[i-1])+(a[2*n-i]!=a[2*n-i+1]),nk=k+(a[i]!=a[i-1]);
		ad(f[i-1][nj][nk],f[i][j][k]);
		rep(o,1,nk-1)
			ad(f[i-1][nj-(nk-o-1)][o],f[i][j][k]);
		rep(o,nk+1,nj)
			ad(f[i-1][nj-(o-nk-1)][nk+1],f[i][j][k]);
	}int res=0;
	rep(i,1,2*n-1)rep(j,1,2*n-1)ad(res,f[1][i][j]);
	cout<<res<<endl;
}

Submission Info

Judge Result