103-算法应用【字符串反转】代码实现

字符串反转

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本文链接：https://www.cnblogs.com/cheng2839

介绍

将字符串倒序组织

分析

我们都知道StringBuilder类有个reverse()方法，可以将字符串反转，但这里考察的是算法实现。

所以我们采取链表存储字符串，然后将链表反转。

实现

下面是用java实现算法：

//本文链接https://www.cnblogs.com/cheng2839
public class $Convert {

    //反转方法
    public static Entry convert(Entry root) {
        if (root == null)
            return null;

        Entry i = root, j = root.next;
        i.next = null;
        while (j != null) {
            Entry head = j.next;
            j.next = i;
            i = j;
            j = head;
        }
        return i;
    }

    //依次打印字符串
    public static void print(String s, Entry n) {
        System.out.println(s);
        while (n != null) {
            System.out.print(n.value + ", ");
            n = n.next;
        }
        System.out.println();
    }

    public static void main(String[] args) {
        String s = "https://www.cnblogs.com/cheng2839";
        Entry root = new Entry("", null);
        Entry head = root;
        for (char c : s.toCharArray()) {
            head.next = new Entry(c, null);
            head = head.next;
        }
        head = root.next;
        print("原始字符串是：", head);
        Entry result = convert(head);
        print("反转后的字符串是：", result);
    }
}

//实体类
class Entry {
    Object value;
    Entry next;
    public Entry(Object value, Entry next) {
        this.value = value;
        this.next = next;
    }
}