The maximum common divisor of T7316 yyy (by) and t7127yyy

The maximum common divisor of T7316 yyy (by) and t7127yyy
Background

Brute force attack

Description

Input/Output Format

Input Format:

 

 

Output Format:

 

 

Input and Output sample input sample #1:

Output sample #1:

Description

 

 

This question uses the principle of rejection and linear screening,

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 1 #include<iostream> 2 #include<cstdio> 3 #include<cstring> 4 #include<cmath> 5 #include<algorithm> 6 #include<queue> 7 #include<stack> 8 #include<cstdlib> 9 #define lli long long int 10 using namespace std;11 const int mod = 998244353;12 const lli maxn=0x7fffff;13 14 const lli MAXN=10000001;15 inline void read(lli &n)16 {17     char c='+';lli x=0;bool flag=0;18     while(c<'0'||c>'9'){c=getchar();if(c=='-')flag=1;}19     while(c>='0'&&c<='9')20     x=(x<<1)+(x<<3)+c-48,c=getchar();21     flag==1?n=-x:n=x;22 }23 lli n,m;24 lli ans=0;25 lli now[MAXN];26 int main()27 {28     read(n);29     read(m);30     if(n>m)31         swap(n,m);32         33     for(lli i=n;i>=1;i--)34     {35         now[i]=1ll*(n/i)*(m/i);36         for(lli j=i+i;j<=n;j+=i)37             now[i]-=now[j];38         ans+=now[i]*i;39     }40     printf("%lld",ans%mod);41     return 0;42 }