[LeetCode] 796. Rotate String

轉自LeetCode

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.

<Solution>
想法如下

• 因為是 shift 的方式來產生不同字串，所以新字串一定會是 A+A 這個字串裡面的 substring

• 首先，檢查長度是不是相同，不同，那一定不可能。相同，再檢查 B 是不是 A+A 裡面的子字串

code 如下

Java

	class Solution {
	public boolean rotateString(String A, String B) {
	if(A.length() != B.length()) {
	return false;
	}
	final String aa = A+A;
	return aa.contains(B);
	}
	}

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