Submission #1200089

#	Time	Username	Problem	Language	Result	Execution time	Memory
1200089		browntoad	Permutation (APIO22_perm)	C++20	85.23 / 100	3 ms	584 KiB

perm

#include "perm.h"
#include <bits/stdc++.h>
using namespace std;
#define ll long long
// #define int ll
#define FOR(i, a, b) for (int i = (a); i < (b); i++)
#define REP(i, n) FOR(i, 0, n)
#define REP1(i, n) FOR(i, 1, n+1)
#define RREP(i, n) for (int i = (n)-1; i >= 0; i--)
#define pii pair<int, int>
#define f first
#define s second
#define pb push_back
#define ALL(x) (x).begin(), (x).end()
#define SZ(x) (int)((x).size())

namespace{
    const ll maxn  = 1e5+5;
    const ll mod = 1e9+7;
    const ll inf = (1ll<<60);
}

pair<int, vector<int>> make_bin(long long k, int cur){ // other method: make with binary
	k--;
	vector<int> ret;
	if (k == 0) return {cur, ret};
	for (int i = 6; i >= 1; i--){
		ll tmp = (1<<i)-1;
		while (k >= tmp){
			k -= tmp;
			vector<int> poo;
			REP(j, i) poo.pb(cur++);
			RREP(j, SZ(poo)) ret.pb(poo[j]);
		}
	}
	reverse(ALL(ret));
	return {cur, ret};
}
pair<int, vector<int>> make_bao(long long k, int cur){
	k--;
	vector<int> ret;
	if (k == 0) return {cur, ret};
	REP(i, k) ret.pb(cur++);
	reverse(ALL(ret));
	return {cur, ret};
}
std::vector<int> construct_permutation(long long k){
	k--; // imma make it a bunch of sums

	vector<int> ret; // initially all reversed
	int cur = 0;
	for (int b = 55; b >= 0; b -= 5){
		ll tmp = (1ll<<b);
		int cnt = 0;
		while(tmp * (cnt+1) - 1 <= k){
			cnt++;
		}
		if (cnt == 0) continue;
		cnt--;

		k -= tmp * (cnt+1) - 1;
		// goal is to have other side of product = cnt+1

		vector<int> ra, rb;
		REP(i, b){
			ra.pb(cur++);
		}
		pair<int, vector<int>> c1 = make_bin(cnt+1, cur), c2 = make_bao(cnt+1, cur);
		if (c1.f < c2.f){
			rb = c1.s;
			cur = c1.f;
		}
		else{
			rb = c2.s;
			cur = c2.f;
		}

		RREP(i, SZ(rb)) ret.pb(rb[i]);
		RREP(i, SZ(ra)) ret.pb(ra[i]);
	}
	reverse(ALL(ret));
	return ret;
}

• Subtask 1: 10 / 10
• Subtask 2: 75.2308 / 90