java - 对字符串进行排序时，数组中的字符被删除

Question

我正在编写一个类来按字典顺序打印给定的字符串，但在 final方法“reverseOrder()”中，数组会自动从中删除值(我想)。方法reverseOrder正在删除选定字符串的一些字符，例如“dkhc”。谢谢

调试显示值已正确添加到数组中。

public class LexicalOrder {
    static String biggerIsGreater(String w) {
        String finalString = "";
        char[] charArr = w.toCharArray();
        int largestX = -1;
        // Find the largest x such that P[x]<P[x+1].
        // (If there is no such x, P is the last permutation.)
        for (int i = 0; i < charArr.length - 1; i++) {
            if (charArr[i] < charArr[i + 1]) {
                largestX = i;
            }
        }
        if (largestX == -1) {
            finalString = "no answer";
        }
        int largestY = -1;
        if (largestX != -1) {
            for (int j = 0; j < charArr.length; j++) {
                if (charArr[largestX] < charArr[j]) {
                    largestY = j;
                }
            }
            charArr = swap(charArr, largestX, largestY);
            charArr = reverseOrder(charArr, largestX + 1);
            finalString = new String(charArr);
        }
        return finalString;
    }

    // Method to swap characters in index largestX and largestY
    public static char[] swap(char[] a, int largestX, int largestY) {
        char temp = a[largestY];
        a[largestY] = a[largestX];
        a[largestX] = temp;
        return a;
    }

    // Method to reverse the order of the array from the index
    // largestX + 1 to n (n being last element of array)
    public static char[] reverseOrder(char[] a, int index) {
        int step = 0;
        char[] newArr = new char[a.length];
        for (int j = 0; j < index; j++) {
            System.out.println(j);
            newArr[j] = a[j]; // adding elements to new arr till index=largestX
            System.out.println(newArr[j] = a[j]);
        }
        for (int i = index; i < a.length; i++) {
            System.out.println(i);
            newArr[index] = a[a.length - step - 1]; // adding remaining values but with reversing order
            System.out.println(newArr[index] = a[a.length - step - 1]);
            step++;
        }
        for (char c : newArr)
            System.out.println(c);
        return newArr;
    }

    public static void main(String[] args) {
        System.out.println(biggerIsGreater("dkhc"));
    }
}

预期的是= hcdk。

但是我得到的是= hk

我运行该方法进行检查，它清楚地将这些元素添加到方法“reverseOrder()”中的“newArr”数组中，如下所示。

0
h
1
c
2
d
3
k

输出 - hk(和两个空格)

由于某种原因，这两个字符被两个空格替换。P.S:我正在按照此处提到的步骤link进行操作

注意:它适用于某些单词，例如“lmno，dcba等”

Answer 1

你错过的是index++。在 reverseOrder 方法中，增量 index++ 将为您提供 hcdk 预期输出。

public static char[] reverseOrder(char[] a, int index) {
        int step = 0;
        char[] newArr = new char[a.length];
        for (int j = 0; j < index; j++) {
            System.out.println(j);
            newArr[j] = a[j]; // adding elements to new arr till index=largestX
            System.out.println(newArr[j] = a[j]);
        }
        for (int i = index; i < a.length; i++) {
            System.out.println(i);
            newArr[index] = a[a.length - step - 1]; // adding remaining values
                                                    // but with reversing order
            System.out.println(newArr[index] = a[a.length - step - 1]);
            step++;index++;
        }
        for (char c : newArr)
            System.out.println(c);
        return newArr;
    }

在您的情况下，由于数组中的 2 和 3 项为空，索引值不会增加。