HDU 6069 Counting Divisors(数论)

xiaoxiao2021-02-28  74

Description Input 第一行一整数T表示用例组数,每组用例输入三个整数l,r,k (1<=T<=15,1<=l<=r<=1e12,r-l<=1e6,1<=k<=1e7) Output 对于每组用例,输出答案 Sample Input 3 1 5 1 1 10 2 1 100 3 Sample Output 10 48 2302 Solution Code

#include<cstdio> #include<cstring> using namespace std; typedef long long ll; const int maxn=1000011,mod=998244353; int mark[maxn],prime[maxn],res=0; void get_prime(int n=1000000) { for(int i=2;i<=n;i++) { if(!mark[i])mark[i]=prime[res++]=i; for(int j=0;j<res&&prime[j]*i<=n;j++) { mark[i*prime[j]]=prime[j]; if(i%prime[j]==0) break; } } } int T,k,n,ans[maxn]; ll l,r,a[maxn]; int Solve() { for(int i=0;i<res&&prime[i]*prime[i]<=r;i++) { int p=prime[i]; ll t=((l+p-1)/p)*p; for(int j=t-l+1;j<=n;j+=p) { int num=0; while(a[j]%p==0)a[j]/=p,num++; ans[j]=(ll)ans[j]*((ll)k*num%mod+1)%mod; } } int sum=0; for(int i=1;i<=n;i++) { if(a[i]>1)ans[i]=(ll)ans[i]*(k+1)%mod; sum=(sum+ans[i])%mod; } return sum; } int main() { get_prime(); scanf("%d",&T); while(T--) { scanf("%I64d%I64d%d",&l,&r,&k); n=r-l+1; for(int i=1;i<=n;i++)a[i]=l+i-1,ans[i]=1; printf("%d\n",Solve()); } return 0; }
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