Question

我希望生成显示不同的不同/唯一数字组合的结果。

例如：如果数字是4位数，即4789，则输出格式为478,789,489,479（仅按递增顺序）。我的代码是：

import java.util.Arrays;
import java.util.HashSet;
import java.util.Random;
import java.util.Scanner;

public class Permutation{
    static void permute(int[] a, int k) {
        int temp;
        if (k == a.length) {
            for (int i = 0; i < a.length - 1; i++) {
                for (int j = i + 1; j < a.length - 1; j++) {
                     if (a[i] > a[j]) {
                        temp = a[i];
                        a[i] = a[j];
                        a[j] = temp;
                     }
                  }
            System.out.print(a[i]);
            }
        System.out.println();
        } else {
            int tempLength = (a.length);
            for (int i = k; i < tempLength; i++) {
                temp = a[k];
                a[k] = a[i];
                a[i] = temp;
                permute(a, k + 1);
            }
        }
    }

    public static void main(String args[]) {

        Scanner sc = new Scanner(System.in);
        System.out.println("Enter the length of list: ");
        int N = sc.nextInt();
        int[] sequence = new int[N];
        System.out.println("---------");
        for (int i = 0; i < N; i++)
            {
        sequence[i] = sc.nextInt();
            }
        System.out.println("The original sequence is: ");
        for (int i = 0; i < N; i++){
        System.out.print(sequence[i] + " ");
        System.out.println("\nThe permuted sequences are: ");
        permute(sequence, 0);
        sc.close();
    }}

以上程序的输出是：

Enter the length of list: 4
---------
1
2
7
8
The original sequence is: 
1 2 7 8 

The permuted sequences are: 

127,128,128,127,178,127,127,128,128,127,178,127,
127,128,128,127,178,127,278,127,127,128,178,127

因此，此结果显示一些重复元素。我想避免在数组中显示这样的重复元素。在上面的代码中，我期待输出：127,128,178,278 帮助，提前谢谢。

Answer 1

您可以使用StringBuilder：

private static String[] getDigitsArray(String str) {
    StringBuilder sb = new StringBuilder(str);
    sb.deleteCharAt(3).append(",")
            .append(new StringBuilder(str).deleteCharAt(0)).append(",")
            .append(new StringBuilder(str).deleteCharAt(1)).append(",")
            .append(new StringBuilder(str).deleteCharAt(2));
    return sb.toString().split(",");
}

简单使用：

String[] array = getDigitsArray("4789");
System.out.println("Result: "+Arrays.toString(array));

结果是：

Result: [478, 789, 489, 479]

对于每4个数字string，你可以使用上面的代码，它会返回一个array，里面有元素，然后你可以做你想要的。

避免打印重复

1 个答案: