Integer to English Words

class Translator {
public:
    vector<pair<int, string>> numToEng = {
        {1000000000, "Billion"}, {1000000, "Million"}, {1000, "Thousand"},
        {100, "Hundred"}, {90, "Ninety"}, {80, "Eighty"}, {70, "Seventy"},
        {60, "Sixty"}, {50, "Fifty"}, {40, "Forty"}, {30, "Thirty"},
        {20, "Twenty"}, {19, "Nineteen"}, {18, "Eighteen"}, {17, "Seventeen"},
        {16, "Sixteen"}, {15, "Fifteen"}, {14, "Fourteen"}, {13, "Thirteen"},
        {12, "Twelve"}, {11, "Eleven"}, {10, "Ten"}, {9, "Nine"}, {8, "Eight"},
        {7, "Seven"}, {6, "Six"}, {5, "Five"}, {4, "Four"}, {3, "Three"},
        {2, "Two"}, {1, "One"}
    };
    
    string integerToEnglish(int value) {
        if (value == 0) {
            return "Zero";
        }
    
        for (auto& [num, text] : numToEng) {
            if (value >= num) {
                string head = (value >= 100) ? integerToEnglish(value / num) + " " : "";
                string middle = text;
                string tail = (value % num == 0) ? "" : " " + integerToEnglish(value % num);
    
                return head + middle + tail;
            }
        }
    
        return "";
    }
};

Translate an integer into its English words representation using C++. The solution employs a class named Translator that includes a method integerToEnglish. Here's how you can understand and utilize this solution:

• The Translator class possesses a vector of pair<int, string> named numToEng, which stores numbers and their corresponding English words from highest (Billion) to lowest (One). This helps map significant numerical values to their respective word forms.

• The integerToEnglish method takes an integer value as input and returns its English words representation. If the input value is zero, the function directly returns the string "Zero".

• Utilize a loop to iterate through the numToEng vector. Check each number to see if the input value is greater than or equal to the number in the pair.

• Construct the string in three components:

  • head: If the number is greater than or equal to 100, recursively calculate the English representation for the quotient of the division of value by num. Add a space after this part.
  • middle: The word representation of the current number from the vector.
  • tail: If there is a remainder from the division (value % num), recursively call integerToEnglish with this remainder and prepend a space.

• Combine the head, middle, and tail to form the full English phrase for the given number. This helps in recursively breaking down the number into manageable parts which can then be converted into their word equivalents.

• Return the concatenated string which provides the full English representation of the integer.

This methodology ensures accurate translation of an integer to its English words equivalent by recursively segmenting the number according to its size (Billion, Million, etc.), which simplifies understanding and constructing the number in natural language.

class IntWord {
    int num;
    String label;
    
    IntWord(int num, String label) {
        this.num = num;
        this.label = label;
    }
}
    
class NumberConverter {
    private static final List<IntWord> numLabelList = Arrays.asList(
        new IntWord(1000000000, "Billion"), new IntWord(1000000, "Million"),
        new IntWord(1000, "Thousand"), new IntWord(100, "Hundred"),
        new IntWord(90, "Ninety"), new IntWord(80, "Eighty"),
        new IntWord(70, "Seventy"), new IntWord(60, "Sixty"),
        new IntWord(50, "Fifty"), new IntWord(40, "Forty"),
        new IntWord(30, "Thirty"), new IntWord(20, "Twenty"),
        new IntWord(19, "Nineteen"), new IntWord(18, "Eighteen"),
        new IntWord(17, "Seventeen"), new IntWord(16, "Sixteen"),
        new IntWord(15, "Fifteen"), new IntWord(14, "Fourteen"),
        new IntWord(13, "Thirteen"), new IntWord(12, "Twelve"),
        new IntWord(11, "Eleven"), new IntWord(10, "Ten"),
        new IntWord(9, "Nine"), new IntWord(8, "Eight"),
        new IntWord(7, "Seven"), new IntWord(6, "Six"),
        new IntWord(5, "Five"), new IntWord(4, "Four"),
        new IntWord(3, "Three"), new IntWord(2, "Two"),
        new IntWord(1, "One")
    );
    
    public String numberToWords(int num) {
        if (num == 0) {
            return "Zero";
        }
    
        for (IntWord iw : numLabelList) {
            if (num >= iw.num) {
                String prefix = (num >= 100) ? numberToWords(num / iw.num) + " " : "";
                String unit = iw.label;
                String suffix = (num % iw.num == 0) ? "" : " " + numberToWords(num % iw.num);
    
                return prefix + unit + suffix;
            }
        }
    
        return "";
    }
}

The provided Java code defines a class IntWord for associating integer numbers with their English word equivalents. Another class, NumberConverter, includes a method numberToWords which converts any integer into its English word representation. The method uses a list of IntWord objects that map significant numbers like 1, 2, 10, 100, 1000, and so forth up to a billion to their corresponding English words.

Follow these steps to understand the code logic:

1. Check if the input number is zero; if yes, return the string "Zero".
2. Iterate through the list of IntWord objects. For each object, check if the input number is greater than or equal to the object's number value.
3. If it is, compute and concatenate the English word equivalents by geographically dividing the number by the object's number value (for the prefix), obtaining the word from IntWord (for the unit), and getting the remainder of the division operation recursively converted into words (for the suffix).
4. The function forms a complete sentence by combining these components (prefix, unit, suffix), ensuring no extra spaces or ungrammatical sequences appear.

This approach breaks down the input number into manageable segments, each corresponding to a part of the English language expression of the number, effectively transforming numerical values into their linguistic expressions by recursive processing in combination with direct mappings.

Review this code if you need to convert large numbers into words for applications like cheque-writing systems, legal documentation, or any software that requires natural language processing of numeric data. The methodology ensures accuracy, scalability, and ease of maintenance by using clear mappings and simple recursive decomposition.

class NumberConverter:
    # Map of numbers to their respective words
    num_to_word = {
        1000000000: "Billion", 1000000: "Million", 1000: "Thousand",
        100: "Hundred", 90: "Ninety", 80: "Eighty", 70: "Seventy",
        60: "Sixty", 50: "Fifty", 40: "Forty", 30: "Thirty",
        20: "Twenty", 19: "Nineteen", 18: "Eighteen", 17: "Seventeen",
        16: "Sixteen", 15: "Fifteen", 14: "Fourteen", 13: "Thirteen",
        12: "Twelve", 11: "Eleven", 10: "Ten", 9: "Nine", 8: "Eight",
        7: "Seven", 6: "Six", 5: "Five", 4: "Four", 3: "Three",
        2: "Two", 1: "One"
    }
    
    def convertToWords(self, num: int) -> str:
        if num == 0:
            return "Zero"
    
        for key, value in self.num_to_word.items():
            if num >= key:
                lead = (self.convertToWords(num // key) + " ") if num >= 100 else ""
                unit = value
                tail = "" if num % key == 0 else " " + self.convertToWords(num % key)
    
                return lead + unit + tail
    
        return ""

This solution translates a given integer into its corresponding English words using Python. The approach employs recursion and a dictionary for efficient mapping of numbers to their respective word equivalents.

Solution Overview:

• The NumberConverter class contains a dictionary num_to_word where integers map to their word forms. The mapping covers bases from individual numbers (1 to 19), tens (20, 30, ... 90), and higher denominators like 'Hundred', 'Thousand', up to 'Billion'.
• The convertToWords function performs the core conversion:
  • Check for zero case directly, returning the word "Zero".
  • Loop through the dictionary items in descending numerical order:
    • Calculate leading words if the number is greater than or equal to the base (100). This involves a recursive call to process the quotient of the division of num by key.
    • Attach the appropriate scale (like "Thousand" or "Million") based on the current dictionary value.
    • For non-exact multiples, recursively process the remainder of num divided by key.
    • Return the concatenated result as the English word representation of the number.

Key Details:

• Recursion handles both partitoning the number into manageable sections (based on size like hundreds, thousands, etc.) and dealing with non-unit quotas (like processing the number 22 as "Twenty Two").
• This methodology efficiently breaks down the number and systematically translates it, leveraging the predefined dictionary for straightforward lookup and concatenation tasks.

This system is highly effective for converting integers into their English word equivalents, making it useful in applications where numeric values need to be presented in written form.