結果

問題 No.2406 Difference of Coordinate Squared
ユーザー 👑 AngrySadEight
提出日時 2025-01-16 02:15:29
言語 C++17
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 77 ms / 2,000 ms
コード長 4,651 bytes
コンパイル時間 5,028 ms
コンパイル使用メモリ 181,308 KB
実行使用メモリ 26,616 KB
最終ジャッジ日時 2025-01-16 02:15:39
合計ジャッジ時間 5,902 ms
ジャッジサーバーID
（参考情報） 		judge1 / judge2
このコードへのチャレンジ
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ファイルパターン 結果
sample AC * 2
other AC * 55
権限があれば一括ダウンロードができます

ソースコード

diff #
プレゼンテーションモードにする

#include <algorithm>
#include <atcoder/all>
#include <bitset>
#include <cassert>
#include <cmath>
#include <ctime>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <tuple>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>
using namespace std;
using namespace atcoder;
typedef long long ll;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define repr(i, n) for (int i = (int)(n) - 1; i >= 0; i--)
#define repk(i, k, n) for (int i = k; i < (int)(n); i++)
#define all(v) v.begin(), v.end()
#define mod1 1000000007
#define mod2 998244353
#define mod3 100000007
#define vi vector<int>
#define vs vector<string>
#define vc vector<char>
#define vl vector<ll>
#define vb vector<bool>
#define vvi vector<vector<int>>
#define vvc vector<vector<char>>
#define vvl vector<vector<ll>>
#define vvb vector<vector<bool>>
#define vvvi vector<vector<vector<int>>>
#define vvvl vector<vector<vector<ll>>>
#define pii pair<int, int>
#define pil pair<int, ll>
#define pli pair<ll, int>
#define pll pair<ll, ll>
#define vpii vector<pair<int, int>>
#define vpll vector<pair<ll, ll>>
#define vvpii vector<vector<pair<int, int>>>
#define vvpll vector<vector<pair<ll, ll>>>
using mint = modint998244353;
template <typename T>
void debug(T e) {
    cerr << e << endl;
}
template <typename T>
void debug(vector<T> &v) {
    rep(i, v.size()) { cerr << v[i] << " "; }
    cerr << endl;
}
template <typename T>
void debug(vector<vector<T>> &v) {
    rep(i, v.size()) {
        rep(j, v[i].size()) { cerr << v[i][j] << " "; }
        cerr << endl;
    }
}
template <typename T>
void debug(vector<pair<T, T>> &v) {
    rep(i, v.size()) { cerr << v[i].first << " " << v[i].second << endl; }
}
template <typename T>
void debug(set<T> &st) {
    for (auto itr = st.begin(); itr != st.end(); itr++) {
        cerr << *itr << " ";
    }
    cerr << endl;
}
template <typename T>
void debug(multiset<T> &ms) {
    for (auto itr = ms.begin(); itr != ms.end(); itr++) {
        cerr << *itr << " ";
    }
    cerr << endl;
}
template <typename T>
void debug(map<T, T> &mp) {
    for (auto itr = mp.begin(); itr != mp.end(); itr++) {
        cerr << itr->first << " " << itr->second << endl;
    }
}
void debug_out() { cerr << endl; }
template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
    cerr << H << " ";
    debug_out(T...);
}
ll my_pow(ll x, ll n, ll mod) {
    // 　繰り返し二乗法．x^nをmodで割った余り．
    ll ret;
    if (n == 0) {
        ret = 1;
    } else if (n % 2 == 1) {
        ret = (x * my_pow((x * x) % mod, n / 2, mod)) % mod;
    } else {
        ret = my_pow((x * x) % mod, n / 2, mod);
    }
    return ret;
}
ll inv(ll x, ll mod) { return my_pow(x, mod - 2, mod); }
int main() {
    ll N, M;
    cin >> N >> M;
    vector<ll> fact(N + 1);
    fact[0] = 1;
    for (ll i = 0; i < N; i++) {
        fact[i + 1] = (fact[i] * (i + 1)) % mod2;
    }
    vector<ll> inv_val(N + 1);
    inv_val[0] = 1;
    inv_val[1] = 1;
    for (ll i = 2; i <= N; i++) {
        inv_val[i] = (inv_val[mod2 % i] * (mod2 - mod2 / i)) % mod2;
    }
    vector<ll> fact_inv(N + 1);
    fact_inv[0] = 1;
    for (ll i = 0; i < N; i++) {
        fact_inv[i + 1] = (fact_inv[i] * inv_val[i + 1]) % mod2;
    }
    auto comb = [&fact, &fact_inv](ll n, ll r) {
        ll ret;
        if (r < 0) {
            ret = 0;
        } else if (r > n) {
            ret = 0;
        } else {
            ret = (fact[n] * fact_inv[n - r]) % mod2;
            ret = (ret * fact_inv[r]) % mod2;
        }
        return ret;
    };
    ll ans = 0;
    // X+1 方向に進む回数を全探索する
    for (ll i = 0; i <= N; i++) {
        ll dest_x = i - (N - i);
        ll comb_x = comb(N, i);
        if (dest_x == 0) {
            if (M == 0) {
                ans += (comb_x * my_pow(2LL, N, mod2)) % mod2;
                ans %= mod2;
            } else {
                continue;
            }
        } else {
            if (abs(M) % abs(dest_x) != 0) {
                continue;
            }
            ll dest_y = M / dest_x;
            if ((N + dest_y) % 2 == 1) {
                continue;
            }
            ll times_y = (N + dest_y) / 2;
            if (times_y < 0 || times_y > N) {
                continue;
            }
            ll comb_y = comb(N, times_y);
            ans += (comb_x * comb_y) % mod2;
            ans %= mod2;
        }
    }
    // debug(ans);
    ans = (ans * inv(my_pow(4, N, mod2), mod2)) % mod2;
    cout << ans << endl;
}
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