Submission #970479

#	Time	Username	Problem	Language	Result	Execution time	Memory
970479		steveonalex	Permutation (APIO22_perm)	C++17	100 / 100	63 ms	716 KiB

perm

#include <bits/stdc++.h>
#include "perm.h"
 
using namespace std;
 
typedef long long ll;
typedef unsigned long long ull;
 
#define ALL(v) (v).begin(), (v).end()
#define MASK(i) (1LL << (i))
#define GETBIT(mask, i) (((mask) >> (i)) & 1)
 
// mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
mt19937_64 rng(1);
ll rngesus(ll l, ll r){return ((ull) rng()) % (r - l + 1) + l;}
 
ll max(ll a, ll b){return (a > b) ? a : b;}
ll min(ll a, ll b){return (a < b) ? a : b;}
 
ll LASTBIT(ll mask){return mask & (-mask);}
ll pop_cnt(ll mask){return __builtin_popcountll(mask);}
ll ctz(ll mask){return __builtin_ctzll(mask);}
ll clz(ll mask){return __builtin_clzll(mask);}
ll logOf(ll mask){return 63 - clz(mask);}
 
template <class T1, class T2>
    bool minimize(T1 &a, T2 b){
        if (a > b){a = b; return true;}
        return false;
    }
template <class T1, class T2>
    bool maximize(T1 &a, T2 b){
        if (a < b){a = b; return true;}
        return false;
    }
template <class T>
    void printArr(T& a, string separator = " ", string finish = "\n", ostream& out = cout){
        for(auto i: a) out << i << separator;
        out << finish;
    }
template <class T>
    void remove_dup(vector<T> &a){
        sort(ALL(a));
        a.resize(unique(ALL(a)) - a.begin());
    }

struct FenwickTree{
    int n;
    vector<ll> a;

    FenwickTree(int _n){
        n = _n;
        a.resize(n + 1);
    }

    void update(int i, ll v){
        while(i <= n){
            a[i] += v;
            i += LASTBIT(i);
        }
    }

    ll get(int i){
        ll ans = 0;
        while(i > 0){
            ans += a[i];
            i -= LASTBIT(i);
        }
        return ans;
    }
};

ll count_i(vector<int> perm){
    int n = perm.size();
    perm.insert(perm.begin(), -1);
    vector<ll> dp(n+1); dp[0] = 1;
    FenwickTree bit(n+2); bit.update(1, 1);
    ll sum = 1;
    for(int i = 1; i<=n; ++i){
        dp[i] = bit.get(perm[i] + 2);
        bit.update(perm[i] + 2, dp[i]);
        sum += dp[i];
    }
    return sum;
}


vector<int> construct_permutation(ll k){
    int j = 0;
    for(; k >= MASK(j + 1); ++j) ;
    j--;     
    vector<int> ans;
    for(int i = 0; i<=j; ++i) ans.push_back(i);

    ll cur = MASK(j+1);
    while(cur < k){
        ll start = cur;

        vector<int> best_config;
        int l = 0, r = ans.size();

        int n = ans.size();

        FenwickTree pref(n+1);
        pref.update(1, 1);
        for(int j = l; j <= r; ++j) {// inserted position
            FenwickTree suff(n+1); suff.update(n+1, 1);
            ll sum = 1;
            for(int i = r-1; i >= j; --i){
                ll mmb = sum - suff.get(ans[i]+1);
                suff.update(ans[i] + 1, mmb);
                sum += mmb;
            }

            for(int i = l; i <= r; ++i)  { // inserted value
                ll cnt = start + pref.get(i + 1) * (sum - suff.get(i));
                if (cnt <= k && maximize(cur, cnt)) {

                    vector<int> bruh = ans;
                    for(int &t: bruh) if (t >= i) t++;
                    bruh.insert(bruh.begin() + j, i);
                    best_config = bruh;
                }
            }
            if (j < r) pref.update(ans[j] + 2, pref.get(ans[j] + 2));
        }
        ans = best_config;
    }

    return ans;
}

// int main(void){
//     ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);

//     // for(int i = 2; i<=100; ++i){
//     //     vector<int> perm = construct_permutation(i);
//     //     if (count_i(perm) != i){
//     //         cout << i << " " << count_i(perm) << "\n";
//     //         printArr(perm);
//     //         break;
//     //     }
//     // }

//     // clock_t start = clock();

//     // for(int i = 0; i<100; ++i){
//     //     vector<int> perm = construct_permutation(rngesus(5e17, 1e18));
//     //     cout << perm.size() << endl;
//     // }

//     // cout << "Time elapsed: " << clock() - start << "ms\n";

//     return 0;
// }

• Subtask 1: 10 / 10
• Subtask 2: 90 / 90