Submission #981639

#	Time	Username	Problem	Language	Result	Execution time	Memory
981639		crafticat	Permutation (APIO22_perm)	C++17	91.33 / 100	2 ms	428 KiB

perm

#include <bits/stdc++.h>

using namespace std;
using ll = long long;
using pii = pair<int,int>;

std::vector<int> construct_permutation(long long k) {
    k--;
    int ma = 1e9;
    int mi = 0;
    vector<int> data;

    while (k > 0) {
        if (k % 2 == 1) {
            data.push_back(ma--);
            k = (k - 1) / 2;
        } else {
            data.push_back(mi++);
            k--;
        }
    }
    std::reverse(data.begin(), data.end());
    vector<pii> d2(data.size());
    for (int i = 0; i < data.size(); ++i) {
        d2[i] = {data[i],i};
    }
    std::sort(d2.begin(), d2.end());

    vector<int> ans(data.size());
    int iter = 0;
    for (auto [val, ind] : d2) {
        ans[ind] = iter++;
    }
    return ans;
}

#if DEBUG

static long long MX=1e18;

static bool check_permutation(vector<int> v)
{
	sort(v.begin(),v.end());
	for(int i=0;i<v.size();i++)
		if(v[i]!=i) return 0;
	return 1;
}

long long count_increasing(const vector<int>& v) {
  vector<long long> dp(v.size() + 1, 0);
  dp[0] = 1;
  for (int x : v)
  {
  	for (int i = 0; i <= x; i++)
  	{
  		dp[x+1] += dp[i];
  		dp[x+1] = min(dp[x+1],MX+1);
  	}
  }
  long long result = 0;
  for (int i = 0; i <= (int)v.size(); i++){
  	result += dp[i];
  	result = min(result,MX+1);
  }
  return result;
}

int main() {
	int t;
	assert(1 == scanf("%d", &t));
	while(t--)
	{
		long long k;
		assert(1 == scanf("%lld",&k));
		vector<int> ret=construct_permutation(k);
		if(!check_permutation(ret))
		{
			printf("WA: Returned array is not a permutation\n");
			exit(0);
		}
		long long inc=count_increasing(ret);
		if(inc!=k)
		{
			if(inc==MX+1)
				printf("WA: Expected %lld increasing subsequences, found more than %lld\n",k, MX);
			else
				printf("WA: Expected %lld increasing subsequences, found %lld\n",k,inc);
			exit(0);
		}
		printf("%d\n",(int)ret.size());
		for(int i=0;i<ret.size();i++)
		{
			printf("%d",ret[i]);
			if(i+1==ret.size())
				printf("\n");
			else
				printf(" ");
		}
	}
	return 0;
}
#endif

Compilation message (stderr)

perm.cpp: In function 'std::vector<int> construct_permutation(long long int)':
perm.cpp:24:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   24 |     for (int i = 0; i < data.size(); ++i) {
      |                     ~~^~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 81.333333333 / 90