除1,1其他外国x,y不等于 为 x<y 案件 一切y有phi(y)组合 F[x]= phi(i) 2<=i<=x 结果为 2*F[x]+1 Problem A Send a Table Input: Standard Input Output: Standard Output When participating in programming contests, you sometimes face the following problem: You know how to calc…
Send a Table Input: Standard Input Output: Standard Output When participating in programming contests, you sometimes face the following problem: You know how to calcutale the output for the given input values, but your algorithm is way too slow to ev…
Send a TableInput: Standard Input Output: Standard Output When participating in programming contests, you sometimes face the following problem: You know how to calcutale the output for the given input values, but your algorithm is way too slow to eve…
send a table When participating in programming contests, you sometimes face the following problem: You knowhow to calcutale the output for the given input values, but your algorithm is way too slow to everpass the time limit. However hard you try, yo…
Description When participating in programming contests, you sometimes face the following problem: You know how to calcutale the output for the given input values, but your algorithm is way too slow to ever pass the time limit. However hard you try, y…
这道题要找二元组(x, y) 满足1 <= x, y <= n 且x与y互素 那么我就可以假设x < y, 设这时答案为f(n) 那么答案就为2 * f(n) +1(x与y反过来就乘2,加上(1,1)) 那么f(n)可以用欧拉函数求 显然f(n) = phi(2) + phi(3) + --+phi(n) #include<cstdio> #define REP(i, a, b) for(int i = (a); i < (b); i++) using namespac…