[Programmers] 정렬 : k번째수

https://programmers.co.kr/learn/courses/30/lessons/42748

코딩테스트 연습 - K번째수

 

package com.hyosung.algo;

import java.util.Scanner;

public class pro_sort02 {

    static int[] buff;

    static void swap(int[]a, int x, int y) {
        int temp = a[x];
        a[x] = a[y];
        a[y] = temp;
    }

    static void quickSort(int[] a, int left, int right) {
        int pl = left;
        int pr = right;
        int pivot = a[(pl+pr)/2];

        do{
            while(a[pl] < pivot) pl++;
            while(a[pr] > pivot) pr--;

            if(pl <= pr) {
                swap(a, pl++, pr--);
            }
        }while(pl <= pr);

        if(left < pr) quickSort(a, left, pr);
        if(pl < right) quickSort(a, pl, right);
    }


    public static void main(String[] args) {

        int[] array = {1,5,2,6,3,7,4};
        int[][] commands = {
                        {2,5,3},
                        {4,4,1},
                        {1,7,3}
                    };

        int[] aa = Solution(array, commands);

        viewArray(aa);
    }



    static int[] Solution(int[] array, int[][] commands) {
        int[] answer = new int[commands.length];

        for(int i=0; i < commands.length; i++) {

            int start = commands[i][0];
            int end = commands[i][1];
            int k = commands[i][2];

            buff = new int[end-start+1];

            int cnt = 0;
            for(int b=start-1; b < end; b++ ) {
                //System.out.println(array[i]);
                buff[cnt++] = array[b];
            }

            quickSort(buff, 0, buff.length-1);
            viewArray(buff);

            answer[i] = buff[k-1];
            //System.out.println("result ; " + buff[k-1]);
        }



        return answer;
    }

    static void viewArray(int[] a) {
        for(int i=0; i < a.length; i++) {
            System.out.print(a[i] + " ");
        }
    }
}