1935. Maximum Number of Words You Can Type

1935. Maximum Number of Words You Can Type

Difficulty: Easy

Topics: Hash Table, String, Weekly Contest 250

There is a malfunctioning keyboard where some letter keys do not work. All other keys on the keyboard work properly.

Given a string text of words separated by a single space (no leading or trailing spaces) and a string brokenLetters of all distinct letter keys that are broken, return the number of words in text you can fully type using this keyboard.

Example 1:

• Input: text = "hello world", brokenLetters = "ad"
• Output: 1
• Explanation: We cannot type "world" because the 'd' key is broken.

Example 2:

• Input: text = "leet code", brokenLetters = "lt"
• Output: 1
• Explanation: We cannot type "leet" because the 'l' and 't' keys are broken.

Example 3:

• Input: text = "leet code", brokenLetters = "e"
• Output: 0
• Explanation: We cannot type either word because the 'e' key is broken.

Constraints:

• 1 <= text.length <= 104
• 0 <= brokenLetters.length <= 26
• text consists of words separated by a single space without any leading or trailing spaces.
• Each word only consists of lowercase English letters.
• brokenLetters consists of distinct lowercase English letters.

Hint:

1. Check each word separately if it can be typed.
2. A word can be typed if all its letters are not broken.

Solution:

We need to determine how many words in a given string can be fully typed using a keyboard where some keys are broken. The solution involves checking each word in the input string to see if it contains any of the broken letters. If a word does not contain any broken letters, it can be typed completely.

Approach

1. Split the Text into Words: The input string text consists of words separated by single spaces. We split this string into individual words.
2. Create a Set of Broken Letters: Convert the string brokenLetters into a set (or an array) for efficient lookup. This allows us to quickly check if a letter is broken.
3. Check Each Word: For each word, check every character. If any character is found in the set of broken letters, skip the word. Otherwise, increment the count of typable words.
4. Return the Count: After processing all words, return the count of words that can be fully typed without encountering any broken letters.

Let's implement this solution in PHP: 1935. Maximum Number of Words You Can Type

<?php
/**
 * @param String $text
 * @param String $brokenLetters
 * @return Integer
 */
function canBeTypedWords($text, $brokenLetters) {
    ...
    ...
    ...
    /**
     * go to ./solution.php
     */
}

// Test cases
echo canBeTypedWords("hello world", "ad") . "\n";   // Output: 1
echo canBeTypedWords("leet code", "lt") . "\n";     // Output: 1
echo canBeTypedWords("leet code", "e") . "\n";      // Output: 0
?>

Explanation:

1. Splitting the Text: The explode function splits the input string text into an array of words using space as the delimiter.
2. Broken Letters Set: The str_split function converts the string brokenLetters into an array of characters, allowing us to check each character efficiently.
3. Checking Words: For each word, we iterate through its characters. If any character is found in the brokenSet, we mark the word as untypable and move to the next word. If no broken characters are found, we increment the count.
4. Result: The count of typable words is returned after processing all words.

This approach efficiently checks each word for broken characters using a set for quick lookups, ensuring optimal performance even for the upper constraint limits. The solution is straightforward and leverages basic string and array operations to achieve the desired result.

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