Arrays_Strings 翻转字符串 @CareerCup

来源：互联网发布：创维电视怎么连接网络编辑：程序博客网时间：2024/04/28 18:32

原文：

Write code to reverse a C-Style String. (C-String means that “abcd” is represented as five characters, including the null character.)

译文：

写代码翻转一个C风格的字符串。(C风格的意思是"abcd"需要用5个字符来表示，包含末尾的结束字符)

写了多个字符串翻转的方法：

package Arrays_Strings;import java.util.Stack;public class S1_2 {// 首尾位置交换public static String reverse1(String s) {char[] cc = s.toCharArray();int len = s.length();for(int i=0; i<len/2; i++) {char tmp = cc[i];cc[i] = cc[len-1-i];cc[len-1-i] = tmp;}return new String(cc);}// Java库函数public static String reverse2(String s) {return new StringBuilder(s).reverse().toString();}// 反向添加public static String reverse3(String s) {String ret = "";for(int i=s.length()-1; i>=0; i--) {ret += s.charAt(i);}return ret;}// 递归1public static String reverse4(String s) {StringBuilder ret = new StringBuilder();rec(new StringBuilder(s), ret, 0);return ret.toString();}// 不能用String作为param，否则无法改变String的值，建议一律采用StringBuilderpublic static void rec(StringBuilder src, StringBuilder dest, int pos) {if(pos == src.length()) {return;}rec(src, dest, pos+1);dest.append(src.charAt(pos));}// 递归2public static String reverse5(String s) {if(s.length() <= 1) {return s;}return reverse5(s.substring(1)) + s.charAt(0); }// =========================================// 输入“I am a student.”，则输出“student. a am I”public static String reverseSentence1(String s) {// 翻转“I am a student.”中所有字符得到“.tneduts a ma I”，// 再翻转每个单词中字符的顺序得到“students. a am I”String reversedSentence = reverse1(s);String[] ss = reversedSentence.split(" ");String ret = "";for(int i=0; i<ss.length; i++) {ret += reverse1(ss[i]);if(i != ss.length-1) {ret += " ";}}return ret;}// 用一个辅助栈public static String reverseSentence2(String s) {Stack<Character> stack = new Stack<Character>();String ret = "";//  先将整句话倒着进栈for(int i=s.length()-1; i>=0; i--) {char c = s.charAt(i);if(c == ' '){// 进栈前检查是否为" ",如果为TRUE,先将依次POP()while( !stack.isEmpty() ) {ret += stack.pop();}ret += " ";} else{stack.push(c);}}// 栈内可能还有剩下的字符while( !stack.isEmpty() ) {ret += stack.pop();}return ret;}public static void main(String[] args) {String s = "abc";System.out.println(reverse1(s));System.out.println(reverse2(s));System.out.println(reverse3(s));System.out.println(reverse4(s));System.out.println(reverse5(s));s = "I am a student.";System.out.println(reverseSentence1(s));System.out.println(reverseSentence2(s));}}

1 0