2942. Find Words Containing Character

2942. Find Words Containing Character

Difficulty: Easy

Topics: Array, String

You are given a 0-indexed array of strings words and a character x.

Return an array of indices representing the words that contain the character x.

Note that the returned array may be in any order.

Example 1:

• Input: words = ["leet","code"], x = "e"
• Output: [0,1]
• Explanation: "e" occurs in both words: "leet", and "code". Hence, we return indices 0 and 1.

Example 2:

• Input: words = ["abc","bcd","aaaa","cbc"], x = "a"
• Output: [0,2]
• Explanation: "a" occurs in "abc", and "aaaa". Hence, we return indices 0 and 2.

Example 3:

• Input: words = ["abc","bcd","aaaa","cbc"], x = "z"
• Output: []
• Explanation: "z" does not occur in any of the words. Hence, we return an empty array.

Constraints:

• 1 <= words.length <= 50
• 1 <= words[i].length <= 50
• x is a lowercase English letter.
• words[i] consists only of lowercase English letters.

Hint:

1. Use two nested loops.

Solution:

We need to find the indices of words in a given list that contain a specific character. The solution involves iterating through each word and checking if the character is present, then collecting the indices of those words.

Approach

1. Initialize an empty array to store the indices of words that contain the specified character.
2. Iterate through each word in the input list while keeping track of the current index.
3. Check if the character exists in the current word using the strpos function. If the character is found, add the current index to the result array.
4. Return the result array after processing all words.

This approach efficiently checks each word for the presence of the character using a linear scan through the list of words, resulting in a time complexity of O(n*m), where n is the number of words and m is the maximum length of the words. This is efficient given the problem constraints.

Let's implement this solution in PHP: 2942. Find Words Containing Character

<?php
/**
 * @param String[] $words
 * @param String $x
 * @return Integer[]
 */
function findWordsContaining($words, $x) {
    ...
    ...
    ...
    /**
     * go to ./solution.php
     */
}

// Example 1:
$words1 = array("leet", "code");
$x1 = "e";
print_r(findWordsContaining($words1, $x1)); // Output: [0,1]

// Example 2:
$words2 = array("abc", "bcd", "aaaa", "cbc");
$x2 = "a";
print_r(findWordsContaining($words2, $x2)); // Output: [0,2]

// Example 3:
$words3 = array("abc", "bcd", "aaaa", "cbc");
$x3 = "z";
print_r(findWordsContaining($words3, $x3)); // Output: []
?>

Explanation:

• Initialization: We start by creating an empty array $result to hold the indices of words containing the character.
• Iteration: Using a loop, we go through each word in the input array. For each word, we check if the character x is present using strpos, which returns the position of the first occurrence of x or false if not found.
• Check and Collect Indices: If strpos returns a valid position (i.e., not false), we add the current index to $result.
• Return Result: Finally, after processing all words, we return the array of indices.

This solution efficiently handles the constraints and ensures that we correctly identify all words containing the specified character, returning their indices in any order.

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