#532891 (C++17) No.616 へんなソート

• 問題: No.616 へんなソート
• ユーザー: Mister
• 提出日時: 2020-08-18 19:53:52
• 言語: C++17 (gcc 13.3.0 + boost 1.87.0)
• 結果: AC
• 実行時間: 39 ms / 2,000 ms
• コード長: 2,710 bytes
• コンパイル時間: 692 ms
• コンパイル使用メモリ: 73,060 KB
• 最終ジャッジ日時: 2025-01-13 03:25:25
• ジャッジサーバーID （参考情報）: judge4 / judge5

ファイルパターン	結果
sample	AC * 3
other	AC * 27

ソースコード

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#include <iostream>
#include <numeric>
#include <vector>
template <int MOD>
struct ModInt {
    using lint = long long;
    int val;
    // constructor
    ModInt(lint v = 0) : val(v % MOD) {
        if (val < 0) val += MOD;
    };
    // unary operator
    ModInt operator+() const { return ModInt(val); }
    ModInt operator-() const { return ModInt(MOD - val); }
    ModInt inv() const { return this->pow(MOD - 2); }
    // arithmetic
    ModInt operator+(const ModInt& x) const { return ModInt(*this) += x; }
    ModInt operator-(const ModInt& x) const { return ModInt(*this) -= x; }
    ModInt operator*(const ModInt& x) const { return ModInt(*this) *= x; }
    ModInt operator/(const ModInt& x) const { return ModInt(*this) /= x; }
    ModInt pow(lint n) const {
        auto x = ModInt(1);
        auto b = *this;
        while (n > 0) {
            if (n & 1) x *= b;
            n >>= 1;
            b *= b;
        }
        return x;
    }
    // compound assignment
    ModInt& operator+=(const ModInt& x) {
        if ((val += x.val) >= MOD) val -= MOD;
        return *this;
    }
    ModInt& operator-=(const ModInt& x) {
        if ((val -= x.val) < 0) val += MOD;
        return *this;
    }
    ModInt& operator*=(const ModInt& x) {
        val = lint(val) * x.val % MOD;
        return *this;
    }
    ModInt& operator/=(const ModInt& x) { return *this *= x.inv(); }
    // compare
    bool operator==(const ModInt& b) const { return val == b.val; }
    bool operator!=(const ModInt& b) const { return val != b.val; }
    bool operator<(const ModInt& b) const { return val < b.val; }
    bool operator<=(const ModInt& b) const { return val <= b.val; }
    bool operator>(const ModInt& b) const { return val > b.val; }
    bool operator>=(const ModInt& b) const { return val >= b.val; }
    // I/O
    friend std::istream& operator>>(std::istream& is, ModInt& x) noexcept {
        lint v;
        is >> v;
        x = v;
        return is;
    }
    friend std::ostream& operator<<(std::ostream& os, const ModInt& x) noexcept { return os << x.val; }
};
constexpr int MOD = 1000000007;
using mint = ModInt<MOD>;
void solve() {
    int n, k;
    std::cin >> n >> k;
    std::vector<mint> dp(k + 1, 0);
    dp[0] = 1;
    for (int d = 1; d < n; ++d) {
        std::vector<mint> sum(k + 2, 0);
        for (int i = 0; i <= k; ++i) {
            sum[i + 1] = sum[i] + dp[i];
        }
        for (int i = 0; i <= k; ++i) {
            dp[i] = sum[i + 1] - sum[std::max(0, i - d)];
        }
    }
    std::cout << std::accumulate(dp.begin(), dp.end(), mint(0)) << "\n";
}
int main() {
    std::cin.tie(nullptr);
    std::ios::sync_with_stdio(false);
    solve();
    return 0;
}
 
 
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