[Java 알고리즘 문제] (68) 소인수분해

문제 설명

제한사항

• 2 ≤ n ≤ 10,000

해답

import java.util.Arrays;
import java.util.HashSet;
import java.util.Set;

class Solution {
    public int[] solution(int n) {
        Set<Integer> factors = new HashSet<>();
        while (n % 2 == 0) {
            factors.add(2);
            n /= 2;
        }
        for (int i = 3; i <= Math.sqrt(n); i += 2) {
            while (n % i == 0) {
                factors.add(i);
                n /= i;
            }
        }
        if (n > 2) {
            factors.add(n);
        }
        int[] result = new int[factors.size()];
        int index = 0;
        for (int factor : factors) {
            result[index++] = factor;
        }
        Arrays.sort(result);
        return result;
    }
}