#20 · #249 · Group Shifted Strings(移位字符串分组)

Given a list of strings where all strings are of the same length, group all strings that belong to the same shifting sequence. A shifting sequence is formed by rotating every character of a string by the same amount. Return the groups in any order. Constraints: 1 <= strings.length <= 200, 1 <= strings[i].length <= 50.