数组练习-1

 

class test {
    public static void main(String[] args) {
        char letter[] = {'a','l'};
        int num[] = new int[26];
        for(int i = 0;i < letter.length;i++){
            num[letter[i] - 97]++;
        }
        for(int i = 0;i < num.length;i++){
            if(num[i] != 0){
                System.out.println((char)('a' + i) + "--" + num[i]);
            }
        }
    }
}

 

 

 

 

 

import java.util.Scanner;
class test {
    public static void main(String[] args) {
        int arr[] = new int[]{27,67,49,37,57,67,7,71,57,87};
        int temp;
        for(int odd = 0,even = arr.length - 1;odd <= even;odd++,even--){
            if(arr[odd] % 2 == 0 && arr[even] % 2 == 1){
                temp = arr[odd];
                arr[odd] = arr[even];
                arr[even] = temp;                
            }else if(arr[odd] % 2 == 1){
                odd++;
            }else if(arr[even] % 2 == 0){
                even--;
            }
        }
        for(int i = 0;i < arr.length;i++){
            System.out.print(arr[i] + " ");        
        }
    }
}

 

 

class test {
    public static void main(String[] args) {
        int arr[] = new int[]{9,10,6,6,1,9,3,5,6,4};
        int num = 0;
        for(int i = 0;i < arr.length - num;i++){
            for(int j = i + 1;j < arr.length - num;j++){
                if(arr[i] == arr[j]){
                    for(int k = j;k < arr.length - 1 - num;k++){
                        arr[k] = arr[k + 1];
                    }
                    num++;
                }
            }
        }
        int arr_new[] = new int[arr.length - num];
        for(int i = 0;i < arr_new.length;i++){
            arr_new[i] = arr[i];
        }
        for(int i = 0;i < arr_new.length;i++){
            System.out.print(arr_new[i] + " ");
        }
        System.out.println(num);
    }
}

 

 

 

import java.util.Scanner;
class test {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        System.out.println("number");
        int number = scan.nextInt();
        int arr[][] = new int [number][];
        for(int i = 0;i < arr.length;i++){
            arr[i] = new int[i + 1];
        }
        for(int i = 0;i < arr.length;i++){
            arr[i][0] = 1;//放在外层循环中
            arr[i][i] = 1;
            for(int j = 1;j < arr[i].length - 1;j++){//i=1，i=2时，循环没有运行
                arr[i][j] = arr[i - 1][j - 1] + arr[i-1][j];
            }
        }
        for(int i = 0;i < arr.length;i++){
            for(int j = 0;j < arr[i].length;j++){
                System.out.print(arr[i][j] + " ");
            }
            System.out.println();
        }
    }
}