[알고리즘문제풀기] 리스트 자르기

문제

내가 작성한 정답

import java.util.*;
import java.util.stream.*;

class Solution {
    public int[] solution(int n, int[] slicer, int[] num_list) {
        List<Integer> answer = new ArrayList<>();
        for(int i = (n==1)?0:slicer[0]; i<= ((n==2)?num_list.length-1:slicer[1]); i=i+((n==4)?slicer[2]:1)){
            answer.add(num_list[i]);
        }
        return answer.stream().mapToInt(i->i).toArray();
    }
}

다른 사람들의 정답

class Solution {
    public int[] solution(int n, int[] slicer, int[] num_list) {
        int start = n == 1 ? 0 : slicer[0];
        int end = n == 2 ? num_list.length - 1 : slicer[1];
        int step = n == 4 ? slicer[2] : 1;
        int[] answer = new int[(end - start + step) / step];
        for (int i = start, j = 0; i <= end; i += step) {
            answer[j++] = num_list[i];
        }
        return answer;
    }
}


import java.util.Arrays;
import java.util.stream.IntStream;

class Solution {
    public int[] solution(int n, int[] slicer, int[] num_list) {

        int[] answer = null;
        int a = slicer[0], b = slicer[1], c = slicer[2];

        switch (n) {
        case 1:
            answer = Arrays.copyOf(num_list, b + 1);
            break;
        case 2:
            answer = Arrays.copyOfRange(num_list, a, num_list.length);
            break;
        case 3:
            answer = Arrays.copyOfRange(num_list, a, b + 1);
            break;
        case 4:
            answer = IntStream.range(0, (b - a) / c + 1).map(i -> num_list[a + i * c]).toArray();
            break;
        }

        return answer;
    }
}