LeetCode 0273. Integer to English Words Solution in Java, Python, C++, JavaScript, Go & Rust | Explanation + Code

Description

Convert a non-negative integer num to its English words representation.

 

Example 1:

Input: num = 123
Output: "One Hundred Twenty Three"

Example 2:

Input: num = 12345
Output: "Twelve Thousand Three Hundred Forty Five"

Example 3:

Input: num = 1234567
Output: "One Million Two Hundred Thirty Four Thousand Five Hundred Sixty Seven"

 

Constraints:

• 0 <= num <= 231 - 1

Solutions

Solution 1

PythonJavaC++GoTypeScriptJavaScriptC#

class Solution: def numberToWords(self, num: int) -> str: if num == 0: return 'Zero' lt20 = [ '', 'One', 'Two', 'Three', 'Four', 'Five', 'Six', 'Seven', 'Eight', 'Nine', 'Ten', 'Eleven', 'Twelve', 'Thirteen', 'Fourteen', 'Fifteen', 'Sixteen', 'Seventeen', 'Eighteen', 'Nineteen', ] tens = [ '', 'Ten', 'Twenty', 'Thirty', 'Forty', 'Fifty', 'Sixty', 'Seventy', 'Eighty', 'Ninety', ] thousands = ['Billion', 'Million', 'Thousand', ''] def transfer(num): if num == 0: return '' if num < 20: return lt20[num] + ' ' if num < 100: return tens[num // 10] + ' ' + transfer(num % 10) return lt20[num // 100] + ' Hundred ' + transfer(num % 100) res = [] i, j = 1000000000, 0 while i > 0: if num // i != 0: res.append(transfer(num // i)) res.append(thousands[j]) res.append(' ') num %= i j += 1 i //= 1000 return ''.join(res).strip()(code-box)

class Solution { private String[] lt20 = {"", "One", "Two", "Three", "Four", "Five", "Six", "Seven", "Eight", "Nine", "Ten", "Eleven", "Twelve", "Thirteen", "Fourteen", "Fifteen", "Sixteen", "Seventeen", "Eighteen", "Nineteen"}; private String[] tens = {"", "Ten", "Twenty", "Thirty", "Forty", "Fifty", "Sixty", "Seventy", "Eighty", "Ninety"}; private String[] thousands = {"Billion", "Million", "Thousand", ""}; public String numberToWords(int num) { if (num == 0) { return "Zero"; } StringBuilder sb = new StringBuilder(); for (int i = 1000000000, j = 0; i > 0; i /= 1000, ++j) { if (num / i == 0) { continue; } sb.append(transfer(num / i)).append(thousands[j]).append(' '); num %= i; } return sb.toString().trim(); } private String transfer(int num) { if (num == 0) { return ""; } if (num < 20) { return lt20[num] + " "; } if (num < 100) { return tens[num / 10] + " " + transfer(num % 10); } return lt20[num / 100] + " Hundred " + transfer(num % 100); } }(code-box)

class Solution { public: vector<string> lt20 = { "", "One", "Two", "Three", "Four", "Five", "Six", "Seven", "Eight", "Nine", "Ten", "Eleven", "Twelve", "Thirteen", "Fourteen", "Fifteen", "Sixteen", "Seventeen", "Eighteen", "Nineteen"}; vector<string> tens = { "", "Ten", "Twenty", "Thirty", "Forty", "Fifty", "Sixty", "Seventy", "Eighty", "Ninety"}; vector<string> thousands = {"Billion", "Million", "Thousand", ""}; string numberToWords(int num) { if (num == 0) { return "Zero"; } string res; for (int i = 1000000000, j = 0; i > 0; i /= 1000, ++j) { int cur = num / i; if (cur == 0) { continue; } if (!res.empty()) { res += ' '; } res += transfer(cur); if (!thousands[j].empty()) { res += ' '; res += thousands[j]; } num %= i; } return res; } private: string transfer(int num) { if (num == 0) { return ""; } if (num < 20) { return lt20[num]; } if (num < 100) { if (num % 10 == 0) { return tens[num / 10]; } return tens[num / 10] + " " + transfer(num % 10); } if (num % 100 == 0) { return lt20[num / 100] + " Hundred"; } return lt20[num / 100] + " Hundred " + transfer(num % 100); } };(code-box)

func numberToWords(num int) string { if num == 0 { return "Zero" } lt20 := []string{ "", "One", "Two", "Three", "Four", "Five", "Six", "Seven", "Eight", "Nine", "Ten", "Eleven", "Twelve", "Thirteen", "Fourteen", "Fifteen", "Sixteen", "Seventeen", "Eighteen", "Nineteen", } tens := []string{ "", "Ten", "Twenty", "Thirty", "Forty", "Fifty", "Sixty", "Seventy", "Eighty", "Ninety", } thousands := []string{"Billion", "Million", "Thousand", ""} var transfer func(int) string transfer = func(num int) string { if num == 0 { return "" } if num < 20 { return lt20[num] } if num < 100 { if num%10 == 0 { return tens[num/10] } return tens[num/10] + " " + transfer(num%10) } if num%100 == 0 { return lt20[num/100] + " Hundred" } return lt20[num/100] + " Hundred " + transfer(num%100) } res := "" for i, j := 1000000000, 0; i > 0; i, j = i/1000, j+1 { cur := num / i if cur == 0 { continue } if res != "" { res += " " } res += transfer(cur) if thousands[j] != "" { res += " " + thousands[j] } num %= i } return res }(code-box)

function numberToWords(num: number): string { if (num === 0) { return 'Zero'; } const lt20 = [ '', 'One', 'Two', 'Three', 'Four', 'Five', 'Six', 'Seven', 'Eight', 'Nine', 'Ten', 'Eleven', 'Twelve', 'Thirteen', 'Fourteen', 'Fifteen', 'Sixteen', 'Seventeen', 'Eighteen', 'Nineteen', ]; const tens = [ '', 'Ten', 'Twenty', 'Thirty', 'Forty', 'Fifty', 'Sixty', 'Seventy', 'Eighty', 'Ninety', ]; const thousands = ['Billion', 'Million', 'Thousand', '']; const transfer = (n: number): string => { if (n === 0) { return ''; } if (n < 20) { return lt20[n]; } if (n < 100) { if (n % 10 === 0) { return tens[Math.floor(n / 10)]; } return tens[Math.floor(n / 10)] + ' ' + transfer(n % 10); } if (n % 100 === 0) { return lt20[Math.floor(n / 100)] + ' Hundred'; } return lt20[Math.floor(n / 100)] + ' Hundred ' + transfer(n % 100); }; let res = ''; for (let i = 1_000_000_000, j = 0; i > 0; i = Math.floor(i / 1000), ++j) { const cur = Math.floor(num / i); if (cur === 0) { continue; } if (res !== '') { res += ' '; } res += transfer(cur); if (thousands[j] !== '') { res += ' ' + thousands[j]; } num %= i; } return res; }(code-box)

/** * @param {number} num * @return {string} */ var numberToWords = function (num) { if (num === 0) { return 'Zero'; } const lt20 = [ '', 'One', 'Two', 'Three', 'Four', 'Five', 'Six', 'Seven', 'Eight', 'Nine', 'Ten', 'Eleven', 'Twelve', 'Thirteen', 'Fourteen', 'Fifteen', 'Sixteen', 'Seventeen', 'Eighteen', 'Nineteen', ]; const tens = [ '', 'Ten', 'Twenty', 'Thirty', 'Forty', 'Fifty', 'Sixty', 'Seventy', 'Eighty', 'Ninety', ]; const thousands = ['Billion', 'Million', 'Thousand', '']; const transfer = n => { if (n === 0) { return ''; } if (n < 20) { return lt20[n]; } if (n < 100) { if (n % 10 === 0) { return tens[Math.floor(n / 10)]; } return tens[Math.floor(n / 10)] + ' ' + transfer(n % 10); } if (n % 100 === 0) { return lt20[Math.floor(n / 100)] + ' Hundred'; } return lt20[Math.floor(n / 100)] + ' Hundred ' + transfer(n % 100); }; let res = ''; for (let i = 1_000_000_000, j = 0; i > 0; i = Math.floor(i / 1000), ++j) { const cur = Math.floor(num / i); if (cur === 0) { continue; } if (res !== '') { res += ' '; } res += transfer(cur); if (thousands[j] !== '') { res += ' ' + thousands[j]; } num %= i; } return res; };(code-box)

public class Solution { private readonly string[] lt20 = { "", "One", "Two", "Three", "Four", "Five", "Six", "Seven", "Eight", "Nine", "Ten", "Eleven", "Twelve", "Thirteen", "Fourteen", "Fifteen", "Sixteen", "Seventeen", "Eighteen", "Nineteen" }; private readonly string[] tens = { "", "Ten", "Twenty", "Thirty", "Forty", "Fifty", "Sixty", "Seventy", "Eighty", "Ninety" }; private readonly string[] thousands = { "Billion", "Million", "Thousand", "" }; public string NumberToWords(int num) { if (num == 0) { return "Zero"; } string res = ""; for (int i = 1000000000, j = 0; i > 0; i /= 1000, ++j) { int cur = num / i; if (cur == 0) { continue; } if (res.Length > 0) { res += " "; } res += Transfer(cur); if (thousands[j].Length > 0) { res += " " + thousands[j]; } num %= i; } return res; } private string Transfer(int num) { if (num == 0) { return ""; } if (num < 20) { return lt20[num]; } if (num < 100) { if (num % 10 == 0) { return tens[num / 10]; } return tens[num / 10] + " " + Transfer(num % 10); } if (num % 100 == 0) { return lt20[num / 100] + " Hundred"; } return lt20[num / 100] + " Hundred " + Transfer(num % 100); } }(code-box)