Submission #1003137

#	Time	Username	Problem	Language	Result	Execution time	Memory
1003137		vjudge1	Party (INOI20_party)	C++17	7 / 100	188 ms	604 KiB

Main

#include <bits/stdc++.h>

using namespace std;

#define int long long
#define pii pair<int, int>
#define all(v) v.begin(), v.end()
#define oo 1e9

const int MAX = 203, MOD = 1e9 + 7;
int n;
int vis[MAX];
int Hcnt[MAX];
int pw[MAX];

int binpow(int a, int b){
    if(b == 0) return 1;
    if(b & 1) return binpow(a, b - 1) % MOD * a % MOD;
    else return binpow(a * a % MOD, b / 2) % MOD;
}
int inv(int a){
    return binpow(a, MOD - 2);
}

void dfs(int node, int h){
    if(vis[node] || node > n || node < 1) return;
    vis[node] = 1;
    Hcnt[h]++;
    dfs(node * 2, h + 1);
    dfs(node * 2 + 1, h + 1);
    dfs(node / 2, h + 1);
}

void solve(){
    cin >> n;
    int ans = 0;
    for(int i = 1; i <= n; i++){
        for(int j = 0; j <= n; j++){
            vis[j] = 0;
            Hcnt[j] = 0;
        } 
        dfs(i, 0);
        int oth = n;
        for(int j = 0; j <= n; j++){
            if(!Hcnt[j]) break;
            oth -= Hcnt[j];
            ans = (ans + j * (pw[Hcnt[j]] - 1) % MOD * pw[oth] % MOD) % MOD;
        }
    }
    cout << ans * inv(pw[n] - 1) % MOD << '\n';
}

signed main(){
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    int t; cin >> t;
    pw[0] = 1;
    for(int i = 1; i < MAX; i++){
        pw[i] = pw[i - 1] * 2 % MOD;
    }
    while(t--){
        solve();
    }
}

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