Submission #760071

#	Time	Username	Problem	Language	Result	Execution time	Memory
760071		The_Samurai	Party (INOI20_party)	C++17	0 / 100	3068 ms	212 KiB

Main

#include "bits/stdc++.h"

using namespace std;
using ll = long long;

const ll mod = 1e9 + 7;

ll binpow(ll a, int b, ll mod, bool dec = false) {
    ll ans = 1;
    while (b) {
        if (b & 1) {
            ans = ans * a % mod;
        }
        a = a * a % mod;
        b >>= 1;
    }
    if (dec) {
        ans = (ans - 1 + mod) % mod;
    }
    return ans;
}

bool isTwo(ll n) {
    return (1 << (63 - __builtin_clzll(n))) == n;
}

ll n, ans;

int calc(ll x, ll mul) {
    vector<pair<ll, int>> g = {{x, 1}};
    ll others = n;
    for (int h = 0; h <= n; h++) {
        vector<pair<ll, int>> nw;
        ll sum = 0;
        for (auto [v, t]: g) {
            sum += t;
            if (x == v) {
                if (v * 2 <= n) {
                    nw.emplace_back(v * 2, t * 2);
                }
                if (v > 1) {
                    nw.emplace_back(v / 2, 1);
                }
                continue;
            }
            if (isTwo(x / v) and x % v == 0) {
                // parent
                if (v * 2 + 1 <= n) {
                    nw.emplace_back(v * 2 + 1, 1);
                }
                if (v != 1) {
                    nw.emplace_back(v / 2, 1);
                }
                continue;
            }
            if (v * 2 <= n) {
                nw.emplace_back(v * 2, t * 2);
            }
        }
        others -= sum;
        ll k = binpow(2, sum % mod, mod, true) * binpow(2, others % mod, mod) % mod;
//        cout << x << ' ' << h << ' ' << sum << ' ' << k * mul << endl;
        ans = (ans + k * h % mod * mul) % mod;
        if (nw.empty()) {
            break;
        }
        g = nw;
    }
}

int main() {
    int q;
    cin >> q;
    while (q--) {
        cin >> n;
        ans = 0;
        for (ll x = 1; x < n; x *= 2) {
            calc(x, x);
        }
        cout << ans * binpow(binpow(2, n, mod, true), mod - 2, mod) % mod << '\n';
    }
}

// 1 - 1 2 4 8
// 2 - 1 3 8 2 4
// 4 - 1 3 2 3 2 4

Compilation message (stderr)

Main.cpp: In function 'int calc(ll, ll)':
Main.cpp:69:1: warning: no return statement in function returning non-void [-Wreturn-type]
   69 | }
      | ^

• Subtask 1: 0 / 7
• Subtask 2: 0 / 23
• Subtask 3: 0 / 33
• Subtask 4: 0 / 37