class Solution:
    def findWordConcatenation(self, text, words):
        result_indices = []  # List to store the starting indices of valid substrings
        word_len = len(words[0])  # Length of each word
        total_words = len(words)  # Total number of words
        word_freq = {}  # Hashmap to store word frequencies

        # Initialize word frequency hashmap
        for word in words:
            word_freq[word] = word_freq.get(word, 0) + 1

        # Slide the window through the text
        for i in range(len(text) - total_words * word_len + 1):
            curr_window = text[i:i + total_words * word_len]  # Current substring
            curr_word_count = {}  # Hashmap to store word frequencies in the current window

            # Count word frequencies in the current window
            for j in range(0, total_words * word_len, word_len):
                curr_word = curr_window[j:j + word_len]
                curr_word_count[curr_word] = curr_word_count.get(curr_word, 0) + 1

            # Check if the current window contains valid concatenated words
            if curr_word_count == word_freq:
                result_indices.append(i)

        return result_indices