Submission #13826334

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Source Code Expand

#include <iostream>
#include <vector>
#include <algorithm>
using i64 = long long;

constexpr auto pow(long long x, long long n, const long long mod) {
    long long ret = 1;
    while(n > 0) {
        if ((n & 1) == 1) ret = (ret * x) % mod;
        x = (x * x) % mod;
        n >>= 1;
    }
    return ret;
}

constexpr auto inverse(const long long x, const long long p) {
    return pow(x, p - 2, p);
}

int main() {
    constexpr i64 mod = 998244353;
    int n, s;
    std::cin >> n >> s;
    std::vector<int> a(n);
    for (auto &e : a) std::cin >> e;

    const i64 inv = inverse(2, mod);
    std::vector<i64> dp(s + 1);
    dp[0] = 1;
    for (int i = 0; i < n; i++) {
        auto next(dp);
        for (int j = 0; j + a[i] <= s; j++) {
            next[j + a[i]] = (next[j + a[i]] + dp[j] * inv % mod) % mod;
        }
        std::swap(dp, next);
    }

    std::cout << dp.back() * pow(2, n, mod) % mod << std::endl;

    return 0;
}

Submission Info

Judge Result