Problem 72 - Project Euler
40秒。
phi <- 1:10^6 for(i in 2:10^6){ if(phi[i]==i){ #i is prime for(j in seq(i,10^6,i)){ #j has i as prime factor phi[j] <- phi[j]*(i-1)/i #and j is not prime } } } sum(phi)-1
Problem 72 - Project Euler
40秒。
phi <- 1:10^6 for(i in 2:10^6){ if(phi[i]==i){ #i is prime for(j in seq(i,10^6,i)){ #j has i as prime factor phi[j] <- phi[j]*(i-1)/i #and j is not prime } } } sum(phi)-1