PU Valid Word Square

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

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

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

Example 1:

• Input:

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

• Output: true
• Explanation:
  • The first row and first column both read "abcd".
  • The second row and second column both read "bnrt".
  • The third row and third column both read "crmy".
  • The fourth row and fourth column both read "dtye".
  • Therefore, it is a valid word square.

Example 2:

• Input:

[
  "abcd",
  "bnrt",
  "crm",
  "dt"
]

• Output: true
• Explanation:
  • The first row and first column both read "abcd".
  • The second row and second column both read "bnrt".
  • The third row and third column both read "crm".
  • The fourth row and fourth column both read "dt".
  • Therefore, it is a valid word square.

Example 3:

• Input:

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

• Output: false
• Explanation:
  • The third row reads "read" while the third column reads "lead".
  • Therefore, it is NOT a valid word square.

C Solution:

bool validWordSquare(char** words, int wordsSize) {
    int i;
    for (i = 0; i < wordsSize; i++) {
        int j;
        for (j = 0; words[i][j]; j++) {
            if (j >= wordsSize) return false;
            if (!words[j][i]) return false;
            if (words[i][j] != words[j][i]) return false;
        }
    }
    return true;
}

Summary:

• Remember

LeetCode: 422. Valid Word Square