Question

我正在尝试获取每个数组中的第一个和最后一个数字，并找到2的总和并在控制台中将其打印出来。一些指导？不确定如何做到这一点谢谢！这就是我到目前为止它只是打印出阵列。

public class Permutations {
    public static void main(String args[]) {
        List<Integer> permutation = Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);

        for (int i = 0; i < 10; i++) {
            Collections.shuffle(permutation);
        }
        System.out.println("List 1 " + permutation);
        System.out.println("List 2 " + permutation);
        System.out.println("List 3 " + permutation);
        System.out.println("List 4 " + permutation);
        System.out.println("List 5 " + permutation);
        System.out.println("List 6 " + permutation);
        System.out.println("List 7 " + permutation);
        System.out.println("List 8 " + permutation);
        System.out.println("List 9 " + permutation);
        System.out.println("List 10 " + permutation);

    }
}

//print off
    List 1 [2, 3, 6, 10, 1, 4, 7, 9, 8, 5]
    List 2 [2, 3, 6, 10, 1, 4, 7, 9, 8, 5]
    List 3 [2, 3, 6, 10, 1, 4, 7, 9, 8, 5]
    List 4 [2, 3, 6, 10, 1, 4, 7, 9, 8, 5]
    List 5 [2, 3, 6, 10, 1, 4, 7, 9, 8, 5]
    List 6 [2, 3, 6, 10, 1, 4, 7, 9, 8, 5]
    List 7 [2, 3, 6, 10, 1, 4, 7, 9, 8, 5]
    List 8 [2, 3, 6, 10, 1, 4, 7, 9, 8, 5]
    List 9 [2, 3, 6, 10, 1, 4, 7, 9, 8, 5]
    List 10 [2, 3, 6, 10, 1, 4, 7, 9, 8, 5]

Answer 1

您是否考虑过使用List.get

然后你可以简单地做

for (int i = 0; i < 10; i++) {
    Collections.shuffle(permutation);
    System.out.println("List " + (i + 1) + " " + permutation.get(0) + " " + 
         permutation.get(9)  + " sum is " + (permutation.get(0) + permutation.get(9)));
}

当然最好使用数组的长度而不是9

Answer 2

以下是根据您的兴趣汇总某些元素的不同解决方案：

IntStream.of(0, 9).map(permutation::get).sum();

这样做的潜在优势在于，可以轻松扩展您想要求和的项目，或者在不改变解决方案结构的情况下过滤或映射它们。

Java打印排列中的第一个和最后一个整数

2 个答案: