You are given a string array words, consisting of distinct 4-letter strings, each containing lowercase English letters.
A word square consists of 4 distinct words: top, left, right and bottom, arranged as follows:
top forms the top row.bottom forms the bottom row.left forms the left column (top to bottom).right forms the right column (top to bottom).It must satisfy:
top[0] == left[0], top[3] == right[0]bottom[0] == left[3], bottom[3] == right[3]Return all valid distinct word squares, sorted in ascending lexicographic order by the 4-tuple (top, left, right, bottom).
Example 1:
Input: words = ["able","area","echo","also"]
Output: [["able","area","echo","also"],["area","able","also","echo"]]
Explanation:
There are exactly two valid 4-word squares that satisfy all corner constraints:
"able" (top), "area" (left), "echo" (right), "also" (bottom)
top[0] == left[0] == 'a'top[3] == right[0] == 'e'bottom[0] == left[3] == 'a'bottom[3] == right[3] == 'o'"area" (top), "able" (left), "also" (right), "echo" (bottom)
Thus, the answer is [["able","area","echo","also"],["area","able","also","echo"]].
Example 2:
Input: words = ["code","cafe","eden","edge"]
Output: []
Explanation:
No combination of four words satisfies all four corner constraints. Thus, the answer is empty array [].
Constraints:
4 <= words.length <= 15words[i].length == 4words[i] consists of only lowercase English letters.words[i] are distinct.["able","area","echo","also"]
["code","cafe","eden","edge"]