Gym - 101257D !Hasan 【二分 | 推公式】

#include <algorithm>
#include <cstdio>
#include <cstring>
#include <iostream>
#include <queue>
using namespace std;
const int maxn = 2*1e5+100;
int a[maxn];
int main(void)
{
long long n,x,y;
scanf("%I64d %I64d %I64d",&n,&x,&y);
long long l=0,r = 2*1e18;
while(l<r-1)
{
long long mid = (l+r)/2;
long long tmp = mid/x+mid/y;
if(tmp>=n)
r = mid;
else
l = mid;
}
printf("%I64d\n",r);
return 0;
}

#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath>
#include <iostream>
#include <vector>
#include <queue>
#include <set>

using namespace std;
typedef long long LL;

LL x,y,n;
int main()
{
while(scanf("%I64d%I64d%I64d",&n,&x,&y)!=EOF)
{
LL A=(n*y)/(x+y);
LL B=(n*x)/(x+y);
LL m=n-A-B;
LL ans=min(max((A+m)*x,B*y),max(A*x,(B+m)*y));
cout<<ans<<endl;
}
return 0;
}