[Leetcode]796. Rotate String

We are given two strings, A and B.

A shift on A consists of taking string A and moving the leftmost character to the rightmost position. For example, if A = 'abcde', then it will be 'bcdea' after one shift on A. Return True if and only if A can become B after some number of shifts on A.

Example 1:
Input: A = 'abcde', B = 'cdeab'
Output: true

Example 2:
Input: A = 'abcde', B = 'abced'
Output: false

Note:

• A and B will have length at most 100.

题目是判断字符串A见过旋转，能否变成字符串B。

思路是把两个字符串A首位连起来，看字符串B是否是它的子串

class Solution {
public:
    bool rotateString(string A, string B) {
        return (A+A).find(B)<A.length();
    }
};