Day62

알고리즘 코드카타

Find Customer Referee

SELECT name 
FROM Customer
WHERE referee_id != 2
OR referee_id IS NULL
;

문자열 내 마음대로 정렬하기

import java.util.Arrays;

class Solution {
    public String[] solution(String[] strings, int n) {
        return Arrays.stream(strings)
                .sorted((a, b) -> {
                    char ca = a.charAt(n);
                    char cb = b.charAt(n);
                    if (ca == cb) {
                        return a.compareTo(b);
                    }
                    return ca - cb;
                })
                .toArray(String[]::new);
    }
}

k번째 수

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

class Solution {
    public int[] solution(int[] array, int[][] commands) {
        List<Integer> yam = new ArrayList<>();
        for(int[] arr : commands){
            yam.add(
                    Arrays.stream(
                        Arrays.copyOfRange(array, arr[0] - 1, arr[1])
                    ).sorted().toArray()[arr[2] - 1]
            );
        }
        return yam.stream().mapToInt(Integer::intValue).toArray();
    }
}

두 개 뽑아서 더하기

import java.util.ArrayList;
import java.util.List;

class Solution {
    public int[] solution(int[] numbers) {
        List<Integer> list = new ArrayList<>();
        for (int i = 0; i < numbers.length -1; i++) {
            for (int j = i + 1; j < numbers.length; j++) {
                list.add(numbers[i] + numbers[j]);
            }
        }
        return list.stream().mapToInt(Integer::intValue).distinct().sorted().toArray();
    }
}