Greatest Common Divisor of Strings

描述

For two strings s and t, we say "t divides s" if and only if s = t + ... + t (i.e., t is concatenated with itself one or more times).

Given two strings str1 and str2, return the largest string x such that x divides both str1 and str2.

Example 1:

Input: str1 = "ABCABC", str2 = "ABC"
Output: "ABC"

Example 2:

Input: str1 = "ABABAB", str2 = "ABAB"
Output: "AB"

Example 3:

Input: str1 = "LEET", str2 = "CODE"
Output: ""

Constraints:

• 1 <= str1.length, str2.length <= 1000
• str1 and str2 consist of English uppercase letters.

分析

由于 str1 和 str2 可以被同一个x串整除，那么 str1+str2 和 str2+str1 一定是相同的。而且最大的x的长度是 str1 和 str2 长度的最大公约数。

代码

Python

# TODO

Java

// TODO

C++

// Greatest Common Divisor of Strings
class Solution {
public:
    string gcdOfStrings(string str1, string str2) {
        return (str1 + str2 == str2 + str1) ? str1.substr(0, gcd(str1.size(), str2.size())) : "";
    }
};