面试题 01.09 字符串轮转

面试题 01.09. String Rotation LCCI

难度 简单

字符串轮转。给定两个字符串s1和s2，请编写代码检查s2是否为s1旋转而成（比如，waterbottle是erbottlewat旋转后的字符串）。

Given two strings, s1 and s2, write code to check if s2 is a rotation of s1 (e.g.,"waterbottle" is a rotation of"erbottlewat"). Can you use only one call to the method that checks if one word is a substring of another?

Example 1:

Input: s1 = "waterbottle", s2 = "erbottlewat"

Output: True

Example 2:

Input: s1 = "aa", s2 = "aba"

Output: False

思路

• 判断 str1 与 str2 长度是否相等
• 把原字符串直接首尾拼接 str1 + str1
• 判断 str2 是否为 str1 的子串

public class _01_09字符串轮转 {

public boolean isFlipedString(String s1, String s2) {

if (s1 == null || s2 == null) return false;

if (s1.length() != s2.length()) return false;

return (s1 + s1).contains(s2);

}

public static void main(String[] args) {

String s1 = "waterbottle", s2 = "erbottlewat";

boolean b = new _01_09字符串轮转().isFlipedString(s1, s2);

System.out.println("b = " + b);

}

}