|
| 1 | +# 273. Integer to English Words |
| 2 | + |
| 3 | +- Difficulty: Hard. |
| 4 | +- Related Topics: Math, String, Recursion. |
| 5 | +- Similar Questions: Integer to Roman. |
| 6 | + |
| 7 | +## Problem |
| 8 | + |
| 9 | +Convert a non-negative integer `num` to its English words representation. |
| 10 | + |
| 11 | + |
| 12 | +Example 1: |
| 13 | + |
| 14 | +``` |
| 15 | +Input: num = 123 |
| 16 | +Output: "One Hundred Twenty Three" |
| 17 | +``` |
| 18 | + |
| 19 | +Example 2: |
| 20 | + |
| 21 | +``` |
| 22 | +Input: num = 12345 |
| 23 | +Output: "Twelve Thousand Three Hundred Forty Five" |
| 24 | +``` |
| 25 | + |
| 26 | +Example 3: |
| 27 | + |
| 28 | +``` |
| 29 | +Input: num = 1234567 |
| 30 | +Output: "One Million Two Hundred Thirty Four Thousand Five Hundred Sixty Seven" |
| 31 | +``` |
| 32 | + |
| 33 | + |
| 34 | +**Constraints:** |
| 35 | + |
| 36 | + |
| 37 | + |
| 38 | +- `0 <= num <= 231 - 1` |
| 39 | + |
| 40 | + |
| 41 | + |
| 42 | +## Solution |
| 43 | + |
| 44 | +```javascript |
| 45 | +/** |
| 46 | + * @param {number} num |
| 47 | + * @return {string} |
| 48 | + */ |
| 49 | +var numberToWords = function(num) { |
| 50 | + if (num === 0) return 'Zero'; |
| 51 | + var words1 = [ |
| 52 | + 'One', |
| 53 | + 'Two', |
| 54 | + 'Three', |
| 55 | + 'Four', |
| 56 | + "Five", |
| 57 | + "Six", |
| 58 | + 'Seven', |
| 59 | + 'Eight', |
| 60 | + 'Nine', |
| 61 | + ]; |
| 62 | + var words2 = [ |
| 63 | + 'Ten', |
| 64 | + 'Eleven', |
| 65 | + 'Twelve', |
| 66 | + 'Thirteen', |
| 67 | + 'Fourteen', |
| 68 | + 'Fifteen', |
| 69 | + 'Sixteen', |
| 70 | + 'Seventeen', |
| 71 | + 'Eighteen', |
| 72 | + 'Nineteen', |
| 73 | + ]; |
| 74 | + var words3 = [ |
| 75 | + 'Ten', |
| 76 | + 'Twenty', |
| 77 | + 'Thirty', |
| 78 | + 'Forty', |
| 79 | + 'Fifty', |
| 80 | + 'Sixty', |
| 81 | + 'Seventy', |
| 82 | + 'Eighty', |
| 83 | + 'Ninety', |
| 84 | + ]; |
| 85 | + var getStr = function(number) { |
| 86 | + var res = []; |
| 87 | + var num1 = Math.floor(number / 100); |
| 88 | + if (num1 > 0) { |
| 89 | + res.push(`${words1[num1 - 1]} Hundred`); |
| 90 | + } |
| 91 | + number %= 100; |
| 92 | + if (number >= 10 && number <= 19) { |
| 93 | + res.push(words2[number - 10]); |
| 94 | + } else { |
| 95 | + var num2 = Math.floor(number / 10); |
| 96 | + if (num2 > 0) { |
| 97 | + res.push(words3[num2 - 1]); |
| 98 | + } |
| 99 | + number %= 10; |
| 100 | + if (number > 0) { |
| 101 | + res.push(words1[number - 1]); |
| 102 | + } |
| 103 | + } |
| 104 | + return res.join(' '); |
| 105 | + }; |
| 106 | + var res = []; |
| 107 | + [ |
| 108 | + [Math.pow(10, 9), 'Billion'], |
| 109 | + [Math.pow(10, 6), 'Million'], |
| 110 | + [Math.pow(10, 3), 'Thousand'], |
| 111 | + ].forEach(item => { |
| 112 | + var num1 = Math.floor(num / item[0]); |
| 113 | + if (num1 > 0) { |
| 114 | + res.push(`${getStr(num1)} ${item[1]}`); |
| 115 | + } |
| 116 | + num %= item[0]; |
| 117 | + }); |
| 118 | + if (num > 0) { |
| 119 | + res.push(getStr(num)); |
| 120 | + } |
| 121 | + return res.join(' '); |
| 122 | +}; |
| 123 | +``` |
| 124 | + |
| 125 | +**Explain:** |
| 126 | + |
| 127 | +nope. |
| 128 | + |
| 129 | +**Complexity:** |
| 130 | + |
| 131 | +* Time complexity : O(log(n)). |
| 132 | +* Space complexity : O(log(n)). |
0 commit comments