Sorting and Searching(정렬, 이분검색과 결정알고리즘) - 선택 정렬 / 버블 정렬 / 삽입 정렬 / 좌표 정렬

 선택 정렬

 

import java.util.*;
class Main {	
	public int[] solution(int n, int[] arr){
		for(int i=0; i<n-1; i++){
			int idx=i;
			for(int j=i+1; j<n; j++){
				if(arr[j]<arr[idx]) idx=j;
			}
			int tmp=arr[i];
			arr[i]=arr[idx];
			arr[idx]=tmp;
		}
		return arr;
	}
	public static void main(String[] args){
		Main T = new Main();
		Scanner kb = new Scanner(System.in);
		int n=kb.nextInt();
		int[] arr=new int[n];
		for(int i=0; i<n; i++) arr[i]=kb.nextInt();
		for(int x : T.solution(n, arr)) System.out.print(x+" ");
	}
}

 

 

 버블 정렬

 

import java.util.*;
class Main {	
	public int[] solution(int n, int[] arr){
		for(int i=0; i<n-1; i++){
			for(int j=0; j<n-i-1; j++){
				if(arr[j]>arr[j+1]){
					int tmp=arr[j];
					arr[j]=arr[j+1];
					arr[j+1]=tmp;
				}
			}	
		}
		return arr;
	}
	public static void main(String[] args){
		Main T = new Main();
		Scanner kb = new Scanner(System.in);
		int n=kb.nextInt();
		int[] arr=new int[n];
		for(int i=0; i<n; i++) arr[i]=kb.nextInt();
		for(int x : T.solution(n, arr)) System.out.print(x+" ");
	}
}

 

 삽입 정렬

 

import java.util.*;
class Main {	
	public int[] solution(int n, int[] arr){
		for(int i=1; i<n; i++){
			int tmp=arr[i], j;
			for(j=i-1; j>=0; j--){
				if(arr[j]>tmp) arr[j+1]=arr[j];
				else break;
			}
			arr[j+1]=tmp;
		}
		return arr;
	}
	public static void main(String[] args){
		Main T = new Main();
		Scanner kb = new Scanner(System.in);
		int n=kb.nextInt();
		int[] arr=new int[n];
		for(int i=0; i<n; i++) arr[i]=kb.nextInt();
		for(int x : T.solution(n, arr)) System.out.print(x+" ");
	}
}

 

 좌표 정렬

 

import java.util.*;

class Point implements Comparable<Point>{ // 포인트 클래스 객체를 정렬
    public int x, y;
    Point(int x, int y){
        this.x = x;
        this.y = y;
    }
    // ------> 정렬
    //this   0

    @Override
    public int compareTo(Point o){
        if(this.x == o.x) return this.y - o.y; // 오름차순
        else return this.x - o.x; // 오름차순
    }
}

class Main {
    public static void main(String[] args){
        Scanner kb = new Scanner(System.in);
        int n=kb.nextInt();
        ArrayList<Point> arr=new ArrayList<>();
        for(int i=0; i<n; i++){
            int x=kb.nextInt();
            int y=kb.nextInt();
            arr.add(new Point(x, y));
        }
        Collections.sort(arr); // Comparable 인터페이스 통해서 Point 객체 정렬
        for(Point o : arr) System.out.println(o.x+" "+o.y);
    }
}