Submission #838437

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Source Code Expand

#include <bits/stdc++.h>

#define _overload(_1,_2,_3,name,...) name
#define _rep(i,n) _range(i,0,n)
#define _range(i,a,b) for(int i=int(a);i<int(b);++i)
#define rep(...) _overload(__VA_ARGS__,_range,_rep,)(__VA_ARGS__)

#define _rrep(i,n) _rrange(i,n,0)
#define _rrange(i,a,b) for(int i=int(a)-1;i>=int(b);--i)
#define rrep(...) _overload(__VA_ARGS__,_rrange,_rrep,)(__VA_ARGS__)

#define _all(arg) begin(arg),end(arg)
#define uniq(arg) sort(_all(arg)),(arg).erase(unique(_all(arg)),end(arg))
#define getidx(ary,key) lower_bound(_all(ary),key)-begin(ary)
#define clr(a,b) memset((a),(b),sizeof(a))
#define bit(n) (1LL<<(n))
#define popcount(n) (__builtin_popcountll(n))

template<class T>bool chmax(T &a, const T &b) { return (a<b)?(a=b,1):0;}
template<class T>bool chmin(T &a, const T &b) { return (b<a)?(a=b,1):0;}

using namespace std;

using ll=long long;

const ll mod=1000000007LL;

inline ll extgcd(ll a,ll b,ll& x,ll& y){x=1,y=0;ll g=a;if(b!=0) g=extgcd(b,a%b,y,x),y-=a/b*x;return g;}
inline ll ADD(const ll &a, const ll &b,const ll &mod) { return a+b<mod?a+b:a+b-mod;}
inline ll SUB(const ll &a, const ll &b,const ll &mod) { return a-b>=0?a-b:a-b+mod;}
inline ll MUL(const ll &a, const ll &b,const ll &mod) { return (1LL*a*b)%mod;}
inline ll INV(ll a,ll mod){ll x,y;extgcd(a,mod,x,y);return (x%mod+mod)%mod;}
inline ll DIV(const ll &a, const ll &b,const ll &mod) {return MUL(a,INV(b,mod),mod);}
inline ll POW(ll a,ll n,ll mod){ll b=1LL;for(a%=mod;n;a=MUL(a,a,mod),n>>=1)if(n&1) b=MUL(b,a,mod); return b;}

ll dp[310][310][310];

string s;

int main(void){
	int n;
	cin >> n >> s;

	if(n>300) return 0;

	const int m=s.size();
	dp[0][0][0]=1LL;
	
	rep(i,n)rep(j,m+1)rep(k,n+1){
		if(k==0 && j!=m && s[j]=='0') 
			dp[i+1][j+1][k]=ADD(dp[i+1][j+1][k],dp[i][j][k],mod);
		else
			dp[i+1][j][k+1]=ADD(dp[i+1][j][k+1],dp[i][j][k],mod);

		if(k==0 && j!=m && s[j]=='1') 
			dp[i+1][j+1][k]=ADD(dp[i+1][j+1][k],dp[i][j][k],mod);
		else
			dp[i+1][j][k+1]=ADD(dp[i+1][j][k+1],dp[i][j][k],mod);

		if(k!=0) 
			dp[i+1][j][k-1]=ADD(dp[i+1][j][k-1],dp[i][j][k],mod);
		else
			dp[i+1][max(0,j-1)][k]=ADD(dp[i+1][max(0,j-1)][k],dp[i][j][k],mod);
	}
	cout << dp[n][m][0] << endl;
	return 0;
}

Submission Info

Judge Result