题目 vjudge URL:Counting Divisors (square) Let σ0(n)\sigma_0(n)σ0(n) be the number of positive divisors of nnn. For example, σ0(1)=1\sigma_0(1) = 1σ0(1)=1, σ0(2)=2\sigma_0(2) = 2σ0(2)=2 and σ0(6)=4\sigma_0(6) = 4σ0(6)=4. Let S2(n)=∑i=1nσ0(i2).S_2(n…
DIVCNT2 - Counting Divisors (square) #sub-linear #dirichlet-generating-function Let \sigma_0(n)σ0(n) be the number of positive divisors of nn. For example, \sigma_0(1) = 1σ0(1)=1, \sigma_0(2) = 2σ0(2)=2 and \sigma_0(6) = 4σ0(6)=4. LetS_2(…
Counting Divisors Time Limit: 10000/5000 MS (Java/Others) Memory Limit: 524288/524288 K (Java/Others)Total Submission(s): 1604 Accepted Submission(s): 592 Problem Description In mathematics, the function d(n) denotes the number of divisors of p…
Part 1:杜教筛进阶在了解了杜教筛基本应用,如$\sum_{i=1}^n\varphi(i)$的求法后,我们看一些杜教筛较难的应用.求$\sum_{i=1}^n\varphi(i)*i$考虑把它与$id$函数狄利克雷卷积后的前缀和.$$\sum_{i=1}^n\sum_{d|i}\varphi(d)*d*\frac id=\sum_{i=1}^ni^2$$枚举$T=\frac id$,原式化为$$\sum_{T=1}^nT\sum_{d=1}^{\lfloor\frac nT\rfloor}…
Counting Divisors Time Limit: 10000/5000 MS (Java/Others) Memory Limit: 524288/524288 K (Java/Others)Total Submission(s): 3170 Accepted Submission(s): 1184 Problem Description In mathematics, the function d(n) denotes the number of divisors of…
Counting Divisors Time Limit: 10000/5000 MS (Java/Others) Memory Limit: 524288/524288 K (Java/Others) Problem Description In mathematics, the function d(n) denotes the number of divisors of positive integer n. For example, d(12)=6 because 1,2,3,4,…