[Java] 9. 배열_예제

[예제 ①] 총합과 평균 구하기

public class exCode {
    public static void main(String[] args) {
        int sum = 0;
        float average = 0f;

        int[] score = {88, 100, 76, 84, 94};

        for (int i = 0; i < score.length; i++) {
            sum += score[i];
        }
        
        average = sum/(float)score.length;

        System.out.println("총점 : " + sum);
        System.out.println("평균 : " + average);
    }
}

[실행 결과]

 

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[예제 ②] 최대값, 최소값 찾기

public class exCode {
    public static void main(String[] args) {
        int[] score = {80, 90,95, 82, 100, 76};

        int max = 0;
        int min = score[0];

        for(int i=0; i< score.length; i++){
            if(score[i]>max){
                max = score[i];
            } else if (score[i]<min){
                min = score[i];
            }
        }

        System.out.println("최대값 : " + max);
        System.out.println("최소값 : " + min);
    }
}

[실행 결과]

 

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[예제 ③] shuffle_카드섞기

public class exCode {
    public static void main(String[] args) {
        int[] nums = new int[10];

        for (int i = 0; i < nums.length; i++) {
            nums[i] = i;
            System.out.print(nums[i]);
        }
        System.out.println();

        //shuffle
        for (int i = 0; i < 100; i++) {
            int n = (int) (Math.random() * 10);
            int temp = nums[0];
            nums[0] = nums[n];
            nums[n] = temp;
        }

        for (int numsPr : nums) {
            System.out.print(numsPr);
        }
    }
}

[실행 결과]

 

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[예제 ④] shuffle2_로또번호 생성하기

public class exCode {
    public static void main(String[] args) {
        int[] lotto = new int[45];

        for(int i=0; i<lotto.length; i++){
            lotto[i] = i+1;
        }

        int temp = 0;
        int j = 0;
        
        for(int i=0; i<6; i++){
            j = (int)(Math.random()*45);
            temp = lotto[i];
            lotto[i] = lotto[j];
            lotto[j] = temp;
        }

        for(int i=0; i<6; i++){
            System.out.printf("ball[%d] = %d%n", i, lotto[i]);
        }
    }
}

[실행 결과]

 

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[예제 ⑤] 임의의 값으로 배열 채우기 

import java.util.Arrays;

public class exCode {
    public static void main(String[] args) {
       int[] code = {-4, -1, 3, 6, 11};
       int[] arr = new int[10];

       for(int i=0; i<arr.length; i++){
           int temp = (int)(Math.random()* code.length);
           arr[i] = code[temp];
       }

        System.out.println(Arrays.toString(arr));
    }
}

[실행 결과]

 

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[예제 ⑥] 배열 요소 정렬하기

public class exCode {
    public static void main(String[] args) {
        int[] nums = new int[10];

        for(int i=0; i<nums.length; i++){
            System.out.print(nums[i] = (int)(Math.random()*10));
        }
        System.out.println();

        //버블 정렬 알고리즘
        for(int i=0; i<nums.length-1; i++){
            boolean changed = false;

            for(int j=0; j<nums.length-1-i; j++){
                if(nums[j] > nums[j+1]){
                    int temp = nums[j];
                    nums[j] = nums[j+1];
                    nums[j+1] = temp;
                    changed = true;
                }
            }

            if(!changed) break;

            for(int k=0; k<nums.length; k++){
                System.out.print(nums[k]);
            }
            System.out.println();
        }
    }
}

[실행 결과]

 

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[예제 ⑦] 각 배열 요소의 빈도 수 구하기

public class exCode {
    public static void main(String[] args) {
        int[] nums = new int[10];
        int[] counter = new int[10];

        for(int i=0; i<nums.length; i++){
            nums[i] = (int)(Math.random()*10);
            System.out.print(nums[i]);
        }
        System.out.println();

        for(int i=0; i<nums.length; i++){
            counter[nums[i]]++;
        }

        for(int i=0; i<nums.length; i++){
            System.out.printf("%d의 개수 : %d%n", i, counter[i]);
        }
    }
}

[실행 결과]

 

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[예제 ⑧] 2차원 좌표에 위치 표시하기

import java.util.Scanner;

public class exCode {
    public static void main(String[] args) {
        final int SIZE = 10;
        int x = 0;
        int y = 0;

        char[][] board = new char[SIZE][SIZE];
        byte[][] shipBoard = {
                {0, 0, 0, 0, 0, 0, 1, 0, 0},
                {1, 1, 1, 1, 0, 0, 1, 0, 0},
                {0, 0, 0, 0, 0, 0, 1, 0, 0},
                {0, 0, 0, 0, 0, 0, 1, 0, 0},
                {0, 0, 0, 0, 0, 0, 0, 0, 0},
                {1, 1, 0, 1, 0, 0, 0, 0, 0},
                {0, 0, 0, 1, 0, 0, 0, 0, 0},
                {0, 0, 0, 1, 0, 0, 0, 0, 0},
                {0, 0, 0, 0, 0, 1, 1, 1, 0},
        };

        for (int i = 0; i < SIZE; i++) {
            board[0][i] = board[i][0] = (char) (i + '0');
        }

        Scanner scan = new Scanner(System.in);

        while (true) {
            System.out.printf("좌표를 입력하세요. (종료는 00) : ");
            String input = scan.nextLine();

            if (input.length() == 2) {
                x = input.charAt(0) - '0';
                y = input.charAt(1) - '0';
                if (x == 0 && y == 0) break;
            }

            if (input.length() != 2 || x <= 0 || x >= SIZE || y <= 0 || y >= SIZE) {
                System.out.println("잘못된 입력입니다. 다시 입력해주세요.");
                continue;
            }

            board[x][y] = shipBoard[x - 1][y - 1] == 1 ? 'O' : 'X';

            for (int i = 0; i < SIZE; i++) {
                System.out.println(board[i]);
            }
            System.out.println();
        }
    }
}

[실행 결과]

 

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[예제 ⑨] 빙고판에서 입력받은 숫자 지우기

import java.util.Scanner;

public class exCode {
    public static void main(String[] args) {
        final int SIZE = 5;
        int x = 0, y = 0, num = 0;

        int[][] bingo = new int[SIZE][SIZE];
        Scanner scan = new Scanner(System.in);

        for (int i = 0; i < SIZE; i++) {
            for (int j = 0; j < SIZE; j++) {
                bingo[i][j] = i * SIZE + j + 1;
            }
        }

        //shuffle
        for (int i = 0; i < SIZE; i++) {
            for (int j = 0; j < SIZE; j++) {
                x = (int) (Math.random() * SIZE);
                y = (int) (Math.random() * SIZE);

                int temp = bingo[i][j];
                bingo[i][j] = bingo[x][y];
                bingo[x][y] = temp;
            }
        }

        do {
            for (int i = 0; i < SIZE; i++) {
                for (int j = 0; j < SIZE; j++) {
                    System.out.printf("%2d ", bingo[i][j]);
                }
                System.out.println();
            }
            System.out.println();

            System.out.printf("1~%d의 숫자를 입력하세요. (종료는 0) : ", SIZE * SIZE);
            String temp = scan.nextLine();
            num = Integer.parseInt(temp);

            outer:
            for (int i = 0; i < SIZE; i++) {
                for (int j = 0; j < SIZE; j++) {
                    if (bingo[i][j] == num) {
                        bingo[i][j] = 0;
                        break outer;
                    }
                }
            }
        } while (num != 0);
    }
}

[실행 결과]

 

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[예제 ⑩] 영단어의 뜻 맞추기

import java.util.Scanner;

public class exCode {
    public static void main(String[] args) {
        String[][] words = {
                {"apple", "사과"},
                {"banana", "바나나"},
                {"grape", "포도"}
        };

        Scanner scan = new Scanner(System.in);

        for(int i=0; i< words.length; i++){
            System.out.printf("Q%d. %s의 뜻은? : ", i+1, words[i][0]);

            String temp = scan.nextLine();
            if(temp.equals(words[i][1])){
                System.out.printf("정답입니다.%n%n");
            } else {
                System.out.printf("틀렸습니다. 정답은 %s입니다. %n%n", words[i][1]);
            }
        }
    }
}

 

[실행 결과]