Given a sequence of words, check whether it forms a valid word square.

A sequence of words forms a valid word square if thekthrow and column read the exact same string, where 0 ≤k< max(numRows, numColumns).

Note:

1. The number of words given is at least 1 and does not exceed 500.
2. Word length will be at least 1 and does not exceed 500.
3. Each word contains only lowercase English alphabeta-z.

class Solution {
    public boolean validWordSquare(List<String> words) {
        if(words == null || words.size() == 0)
            return true;

        int n = words.size();
        if(words.get(0).length() != n)
            return false;

        char[][] t = new char[n][n];
        for(int i = 0; i < n; i++) {
            if(words.get(i).length() > n)
                return false;
            for(int j = 0; j < n; j++) {
                if(j < words.get(i).length()) {
                    t[i][j] = words.get(i).charAt(j);
                } else {
                    t[i][j] = '\0';
                }
            }
        }

        for(int i = 0; i < n; i++) {
            int j = i;
            int k = i;
            while(j < n && k < t[i].length) {
                System.out.println(t[j][i]);
                if(t[j][i] != t[i][k])
                    return false;
                j++;
                k++;
            }
            if(j != k)
                return false;
        }

        return true;
    }
}