제출 #881990

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
881990		vjudge1	홀-짝 수열 (IZhO11_oddeven)	C++17	0 / 100	0 ms	348 KiB

oddeven

#include <bits/stdc++.h>
using namespace std;
#define sp << " " << 
#define int long long
#define vi vector<int>
#define F(xxx,yyy) for (int xxx=1;xxx<=yyy;xxx++)
#define pii pair<int,int>
const int N = 1e5+1,inf = 1e18;
void solve() {
  int n;
  cin >> n;
  int l=1;
  int r=2e9;
  while (l<=r) {
    int m = (l+r) >> 1;
    if (m*(m+1)/2 <= n) l = m+1;
    else r = m-1;
  }
  int x = r*(r-1)/2;
  cout << n+x+(n-r*(r+1)/2)/2 << endl;
}	
    
                  
                             
signed main() { 
  ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
  #ifdef Local
  freopen("in","r",stdin);
  freopen("out","w",stdout);
  #endif
  int t = 1;
  //cin >> t;
	F(i,t) solve();
}

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