Submission #3511729


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#include <bits/stdc++.h>
#include <sys/types.h>
#include <unistd.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))

using namespace std;

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 ll=long long;
using R=long double;
const R EPS=1e-9L; // [-1000,1000]->EPS=1e-8 [-10000,10000]->EPS=1e-7
inline int sgn(const R& r){return(r > EPS)-(r < -EPS);}
inline R sq(R x){return sqrt(max(x,0.0L));}

const int dx[8]={1,0,-1,0,1,-1,-1,1};
const int dy[8]={0,1,0,-1,1,1,-1,-1};

const pid_t pid = getpid();
// Problem Specific Parameter:

template<unsigned MOD>  class ModInt {
public:
	ModInt(): x(0) {}
	ModInt(signed y) : x(y >= 0 ? y % MOD : MOD - (-y) % MOD) {}
	ModInt(signed long long y) : x(y >= 0 ? y % MOD : MOD - (-y) % MOD) {}


	// Arithmetic Oprators
	ModInt &operator+=(ModInt that) {
		if ((x += that.x) >= MOD) x -= MOD; 
		return *this;
	}
	ModInt &operator-=(ModInt that) {
		if ((x += MOD - that.x) >= MOD) x -= MOD; 
		return *this;
	}
	ModInt &operator*=(ModInt that) {
		x = 1LL * x * that.x % MOD;
		return *this;
	}
	ModInt &operator/=(ModInt that) {
		return *this *= ModInt(get<1>(extgcd(that.x, int(MOD))));
	}
	ModInt &operator%=(ModInt that) {
		x %= that.x;
		return *this;
	}

	ModInt &operator+=(const int that) { return *this += ModInt(that);}
	ModInt &operator-=(const int that) { return *this -= ModInt(that);}
	ModInt &operator*=(const int that) { return *this *= ModInt(that);}
	ModInt &operator/=(const int that) { return *this /= ModInt(that);}
	ModInt &operator%=(const int that) { return *this %= ModInt(that);}

	// Comparators
	bool operator <(ModInt that) { return x < that.x; }
	bool operator >(ModInt that) { return x > that.x; }
	bool operator<=(ModInt that) { return x <= that.x; }
	bool operator>=(ModInt that) { return x >= that.x; }
	bool operator!=(ModInt that) { return x != that.x; }
	bool operator==(ModInt that) { return x == that.x; }

	// Utilities
	unsigned getval() const { return x;}
	ModInt operator+(ModInt that) const { return ModInt(*this) += that;}
	ModInt operator-(ModInt that) const { return ModInt(*this) -= that;}
	ModInt operator*(ModInt that) const { return ModInt(*this) *= that;}
	ModInt operator/(ModInt that) const { return ModInt(*this) /= that;}
	ModInt operator%(ModInt that) const { return ModInt(*this) %= that;}
	ModInt operator+(const int that) const { return ModInt(*this) += that;}
	ModInt operator-(const int that) const { return ModInt(*this) -= that;}
	ModInt operator*(const int that) const { return ModInt(*this) *= that;}
	ModInt operator/(const int that) const { return ModInt(*this) /= that;}
	ModInt operator%(const int that) const { return ModInt(*this) %= that;}
	ModInt operator=(const int that) { return *this = ModInt(that);}
	friend istream &operator>>(istream& is, ModInt &that) {ll tmp; is >> tmp; that = ModInt(tmp);return is;}
	friend ostream &operator<<(ostream& os, const ModInt &that) { return os << that.x; }
	
	ModInt power(ll n) const {
		ll b = 1LL, a = x;
		while(n){
			if(n & 1) b = b * a % MOD;
			a = a * a % MOD;
			n >>= 1;
		}
		return ModInt(b);
	}
private:
	unsigned x;
	
	inline auto extgcd(int a, int b) {
		if (b == 0) return make_tuple(a, 1, 0);
		tuple<int, int, int> ret = extgcd(b, a % b);
		swap(get<1>(ret), get<2>(ret));
		get<2>(ret) -= a / b * get<1>(ret);
		return ret;
	}
};

const int mod = 1000000007;
using mint = ModInt<mod>;
const mint ZERO = mint(0);
const mint ONE = mint(1);
const mint TWO = mint(2);

mint dp[5010][5010];

int main(void){
	int n;
	cin >> n;
	string s;
	cin >> s;
	const int k = s.size();

	dp[0][0] = ONE;
	rep(i,n)rep(j,n+1){
		if(dp[i][j] == ZERO) continue;
		dp[i+1][j+1] += TWO * dp[i][j];
		dp[i+1][max(0,j-1)] += dp[i][j];	
	}

	mint cardinality = TWO.power(k);
	mint ans = dp[n][k] / cardinality;
	cout << ans << endl;

	return 0;
}

Submission Info

Submission Time
Task F - Unhappy Hacking
User Hec
Language C++14 (GCC 5.4.1)
Score 800
Code Size 4638 Byte
Status AC
Exec Time 131 ms
Memory 98304 KB

Judge Result

Set Name Sample Sub1 Sub2
Score / Max Score 0 / 0 400 / 400 400 / 400
Status
AC × 3
AC × 23
AC × 44
Set Name Test Cases
Sample 0_01, 0_02, 0_03
Sub1 0_01, 0_02, 1_04, 1_05, 1_06, 1_07, 1_08, 1_09, 1_10, 1_11, 1_12, 1_13, 1_14, 1_15, 1_16, 1_17, 1_18, 1_19, 1_20, 1_21, 1_22, 1_23, 1_24
Sub2 0_01, 0_02, 0_03, 1_04, 1_05, 1_06, 1_07, 1_08, 1_09, 1_10, 1_11, 1_12, 1_13, 1_14, 1_15, 1_16, 1_17, 1_18, 1_19, 1_20, 1_21, 1_22, 1_23, 1_24, 2_25, 2_26, 2_27, 2_28, 2_29, 2_30, 2_31, 2_32, 2_33, 2_34, 2_35, 2_36, 2_37, 2_38, 2_39, 2_40, 2_41, 2_42, 2_43, 2_44
Case Name Status Exec Time Memory
0_01 AC 30 ms 98304 KB
0_02 AC 31 ms 98304 KB
0_03 AC 131 ms 98304 KB
1_04 AC 30 ms 98304 KB
1_05 AC 31 ms 98304 KB
1_06 AC 31 ms 98304 KB
1_07 AC 31 ms 98304 KB
1_08 AC 31 ms 98304 KB
1_09 AC 31 ms 98304 KB
1_10 AC 31 ms 98304 KB
1_11 AC 31 ms 98304 KB
1_12 AC 31 ms 98304 KB
1_13 AC 31 ms 98304 KB
1_14 AC 31 ms 98304 KB
1_15 AC 31 ms 98304 KB
1_16 AC 31 ms 98304 KB
1_17 AC 31 ms 98304 KB
1_18 AC 31 ms 98304 KB
1_19 AC 31 ms 98304 KB
1_20 AC 30 ms 98304 KB
1_21 AC 30 ms 98304 KB
1_22 AC 30 ms 98304 KB
1_23 AC 31 ms 98304 KB
1_24 AC 30 ms 98304 KB
2_25 AC 130 ms 98304 KB
2_26 AC 131 ms 98304 KB
2_27 AC 131 ms 98304 KB
2_28 AC 131 ms 98304 KB
2_29 AC 131 ms 98304 KB
2_30 AC 131 ms 98304 KB
2_31 AC 131 ms 98304 KB
2_32 AC 131 ms 98304 KB
2_33 AC 131 ms 98304 KB
2_34 AC 131 ms 98304 KB
2_35 AC 130 ms 98304 KB
2_36 AC 131 ms 98304 KB
2_37 AC 130 ms 98304 KB
2_38 AC 130 ms 98304 KB
2_39 AC 131 ms 98304 KB
2_40 AC 110 ms 98304 KB
2_41 AC 71 ms 98304 KB
2_42 AC 125 ms 98304 KB
2_43 AC 82 ms 98304 KB
2_44 AC 32 ms 98304 KB