Count Prefixes of a Given String
Intuition\n Describe your first thoughts on how to solve this problem. \nThe problem is to determine how many strings in an array are prefixes of a given string
# Intuition\n<!-- Describe your first thoughts on how to solve this problem. -->\nThe problem is to determine how many strings in an array are prefixes of a given string. A prefix of a string is a substring that starts at the beginning of the string and can be of any length up to the length of the string itself. To solve this problem, we can iterate through each word in the array and check if it is a prefix of the given string using the `startsWith` method.\n\n# Approach\n<!-- Describe your approach to solving the problem. -->\n1. **Initialize a counter**: Start with a counter set to zero to keep track of the number of prefixes found.\n2. **Iterate through the array**: Loop through each string in the `words` array.\n3. **Check for prefix**: For each string, use the `startsWith` method to check if it is a prefix of the string `s`.\n4. **Update the counter**: If a string is a prefix, increment the counter.\n5. **Return the count**: After checking all strings, return the final count.\n\nHere\'s the given code, which implements this approach:\n\n```java\nclass Solution {\n    public int countPrefixes(String[] words, String s) {\n        int count = 0;\n        for (int i = 0; i < words.length; i++) {\n            if (s.startsWith(words[i])) {\n                count++;\n            }\n        }\n        return count;\n    }\n}\n```\n\n# Complexity\n- **Time complexity**:\n  - The `startsWith` method has a time complexity of (O(k)) where (k) is the length of the word being checked.\n  - Since we iterate through each word in the array and `startsWith` is called for each word, the overall time complexity is (O(n cdot k)), where (n) is the number of words and (k) is the average length of the words.\n\n- **Space complexity**:\n  - The space complexity is (O(1)) because we are using only a constant amount of extra space (the integer `count`), irrespective of the input size. The `startsWith` method does not use additional space that scales with the input size.
['Array', 'String', 'Java']