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| 1 | +const zeroToNine = { |
| 2 | + 0: 'Zero', |
| 3 | + 1: 'One', |
| 4 | + 2: 'Two', |
| 5 | + 3: 'Three', |
| 6 | + 4: 'Four', |
| 7 | + 5: 'Five', |
| 8 | + 6: 'Six', |
| 9 | + 7: 'Seven', |
| 10 | + 8: 'Eight', |
| 11 | + 9: 'Nine', |
| 12 | +}; |
| 13 | + |
| 14 | +const tenToNineteen = { |
| 15 | + 10: 'Ten', |
| 16 | + 11: 'Eleven', |
| 17 | + 12: 'Twelve', |
| 18 | + 13: 'Thirteen', |
| 19 | + 14: 'Fourteen', |
| 20 | + 15: 'Fifteen', |
| 21 | + 16: 'Sixteen', |
| 22 | + 17: 'Seventeen', |
| 23 | + 18: 'Eighteen', |
| 24 | + 19: 'Nineteen', |
| 25 | +}; |
| 26 | + |
| 27 | +const twentyToNinety = { |
| 28 | + 2: 'Twenty', |
| 29 | + 3: 'Thirty', |
| 30 | + 4: 'Forty', |
| 31 | + 5: 'Fifty', |
| 32 | + 6: 'Sixty', |
| 33 | + 7: 'Seventy', |
| 34 | + 8: 'Eighty', |
| 35 | + 9: 'Ninety', |
| 36 | +}; |
| 37 | + |
| 38 | +const BILLION = 1000000000; |
| 39 | +const MILLION = 1000000; |
| 40 | +const THOUSAND = 1000; |
| 41 | +const HUNDRED = 100; |
| 42 | +const TEN = 10; |
| 43 | + |
| 44 | +const three = num => { |
| 45 | + const solution = []; |
| 46 | + |
| 47 | + const hundreds = parseInt(num / HUNDRED); |
| 48 | + |
| 49 | + if (hundreds >= 1) { |
| 50 | + solution.push(zeroToNine[hundreds] + ' Hundred'); |
| 51 | + num = num - hundreds * HUNDRED; |
| 52 | + } |
| 53 | + |
| 54 | + if (num && num < 20) { |
| 55 | + solution.push(zeroToNine[num] || tenToNineteen[num]); |
| 56 | + } else { |
| 57 | + const tens = parseInt(num / TEN); |
| 58 | + if (tens) solution.push(twentyToNinety[tens]); |
| 59 | + num = num - tens * TEN; |
| 60 | + if (num) solution.push(zeroToNine[num]); |
| 61 | + } |
| 62 | + |
| 63 | + return solution.join(' '); |
| 64 | +}; |
| 65 | + |
| 66 | +/** |
| 67 | + * @param {number} num Number to be converted to words. |
| 68 | + * @return {string} Result of converting input number to words. |
| 69 | + * @summary Integer to English Words {@link https://leetcode.com/problems/integer-to-english-words/} |
| 70 | + * @description Convert input string to english word representation. |
| 71 | + * Space O(1) - one resulting string. |
| 72 | + * Time O(n) - grows in line with size of the input. |
| 73 | + */ |
| 74 | +const numberToWords = num => { |
| 75 | + if (num < 19) return zeroToNine[num] || tenToNineteen[num]; |
| 76 | + |
| 77 | + const billionCount = num < BILLION ? 0 : parseInt(num / BILLION); |
| 78 | + const millionCount = num < MILLION ? 0 : parseInt((num - billionCount * BILLION) / MILLION); |
| 79 | + const thousandCount = |
| 80 | + num < THOUSAND ? 0 : parseInt((num - billionCount * BILLION - millionCount * MILLION) / THOUSAND); |
| 81 | + const rest = parseInt(num - billionCount * BILLION - millionCount * MILLION - thousandCount * THOUSAND); |
| 82 | + |
| 83 | + const solution = []; |
| 84 | + |
| 85 | + if (billionCount >= 1) solution.push(three(billionCount) + ' Billion'); |
| 86 | + if (millionCount >= 1) solution.push(three(millionCount) + ' Million'); |
| 87 | + if (thousandCount >= 1) solution.push(three(thousandCount) + ' Thousand'); |
| 88 | + if (rest >= 1) solution.push(three(rest)); |
| 89 | + |
| 90 | + return solution.join(' '); |
| 91 | +}; |
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