字符逆序

妖狐艹你老母 2023-06-28 12:29 17阅读 0赞

[https://www.nowcoder.com/practice/cc57022cb4194697ac30bcb566aeb47b?tpId=37&tqId=21329&tPage=6&rp=&ru=%2Fta%2Fhuawei&qru=%2Fta%2Fhuawei%2Fquestion-ranking][https_www.nowcoder.com_practice_cc57022cb4194697ac30bcb566aeb47b_tpId_37_tqId_21329_tPage_6_rp_ru_2Fta_2Fhuawei_qru_2Fta_2Fhuawei_2Fquestion-ranking]

## 一、题目描述 ##

将一个字符串str的内容颠倒过来，并输出。str的长度不超过100个字符。 如：输入“I am a student”，输出“tneduts a ma I”。

## 二、代码实现 ##

1、将字符串存进StringBuilder，并使用其reverse()方法

2、将字符串的每个字符存进栈，利用栈先进后出的特性依次输出

import java.util.Scanner;
    import java.util.Stack;
    
    public class Main {
        public static void main(String[] args) {
            Scanner sc = new Scanner(System.in);
            while (sc.hasNextLine()) {
                String str = sc.nextLine();
                Stack<Character> stack = new Stack<>();
                
                for (int i=0; i<str.length(); i++) {
                    stack.push(str.charAt(i));
                }
                
                while (!stack.isEmpty()) {
                    System.out.print(stack.pop());
                }
            }
        }
    }

3、将字符串的所有字符存进一个新的数组中，并实现reverse()方法直接变动数组中的元素以实现逆序

import java.util.Scanner;
    
    public class Main {
        
        public static void main(String[] args) {
            Scanner sc = new Scanner(System.in);
            while (sc.hasNextLine()) {
                String str = sc.nextLine();
                char[] arr = str.toCharArray();
                reverse(arr, 0, arr.length-1);
                
                /*
                for (int i=0; i<arr.length; i++) {
                    System.out.print(arr[i]);
                }
                */
                //
                //字符数组转成字符串
                String result = new String(arr);
                System.out.println(result);
            }
        }
    
        public static void reverse(char[] arr, int start, int end) {
            while (start < end) {
                char temp = arr[start];
                arr[start] = arr[end];
                arr[end] = temp;
                start++;
                end--;
            }
        }
    }

[https_www.nowcoder.com_practice_cc57022cb4194697ac30bcb566aeb47b_tpId_37_tqId_21329_tPage_6_rp_ru_2Fta_2Fhuawei_qru_2Fta_2Fhuawei_2Fquestion-ranking]: https://www.nowcoder.com/practice/cc57022cb4194697ac30bcb566aeb47b?tpId=37&tqId=21329&tPage=6&rp=&ru=%2Fta%2Fhuawei&qru=%2Fta%2Fhuawei%2Fquestion-ranking