Valid Word Square

Problem

Return True if the list of words forms a word square, meaning the k-th row and the k-th column contain the same sequence of characters wherever both positions exist.

Compare words[i][j] with words[j][i] and fail on any mismatch or out-of-range access. Empty input is trivially valid.

Hint

A position outside the bounds of the transposed word breaks the square.

Test cases

case 1

in: [["abcd","bnrt","crmy","dtye"]]

expected: true

case 2

in: [["ab","ba"]]

expected: true

case 3

in: [["ball","area","read","lady"]]

expected: false

case 4

in: [["a"]]

expected: true

case 5

in: [[]]

expected: true

case 6

in: [["abc","b"]]

expected: false

Starter codePython

def valid_word_square(words):
    # Your code here
    pass

6 test cases · run your code against them in the editor