[AtCoder] D - FizzBuzz Sum Hard

D - FizzBuzz Sum Hard

  • Time : O(n / a + n / b)
  • Space : O(1)
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#include <bits/stdc++.h>

#pragma optimization_level 3
#pragma GCC optimize("Ofast,no-stack-protector,unroll-loops,fast-math,O3")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx")
#pragma GCC optimize("Ofast")//Comment optimisations for interactive problems (use endl)
#pragma GCC target("avx,avx2,fma")
#pragma GCC optimization ("unroll-loops")

struct PairHash {inline std::size_t operator()(const std::pair<int,int> & v) const {return v.first*31+v.second;}};

#define MAX_N 151515
#define INF 987654321
#define EPS 1e-9
#define ll long long
#define pll pair<ll, ll>
#define vpll vector<pll>
#define vall3 vector<array<ll,3>>
#define all3 array<ll,3>
#define all5 array<ll,5>
#define vall5 vector<all5>
#define vll vector<ll>
#define vi vector<int>
#define vs vector<string>
#define usll unordered_set<ll>
#define uspll unordered_set<pll, PairHash>
#define vvs vector<vs>
#define vvll vector<vll>
#define all(a) begin(a), end(a)
#define rall(a) rbegin(a), rend(a)

using namespace std;

ll solve(ll n, ll A, ll B) {
if(A == 1 or B == 1) return 0;
ll now = 1, a = A, b = B;
ll res = 0;
while(now <= n) {
ll mi = min({a, b, n + 1});

res += (mi - now) * (now + mi - 1) / 2;

now = mi + 1;
if(a == mi) a += A;
if(b == mi) b += B;
}
return res;
}

int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
ll tc = 1;
//cin>>tc;
for(ll i = 1; i <= tc; i++) {
ll n, a, b;
cin>>n>>a>>b;
cout<<solve(n,a,b)<<endl;
}
return 0;
}
Author: Song Hayoung
Link: https://songhayoung.github.io/2022/06/15/PS/AtCoder/abc253-d/
Copyright Notice: All articles in this blog are licensed under CC BY-NC-SA 4.0 unless stating additionally.