c++ のfor(int i = 2; i * i <= n; i++) { をrustで書くと、 [code] for i in 2.. { if i * i > n { break; } // 処理 } [/code] となるらしい... なるほど~ [code] use std::collections::HashMap; fn is_prime(n i32) -> bool { for i in 2..(i*i < n) { if(n % i == 0) { return false; } } return n != 1; } fn divisor(n i32) -> Vec<i32> { let mut res: Vec<i32> = Vec::new(); for i in 1..(i*i < n) { if (n % i == 0) { res.push(i); if (i != n / i) { res.push(n / i); } } } return res; } fn prime_factor(n: i32) -> HashMap<i32, i32> { let mut res = HashMap::new(); for i in 2..(i*i <= n) { while (n % i == 0) { res.insert( i, i ); n = n / i; } } if ( n != 1) { res[&n] = 1; } return res; } [/code]
