# 问题 原题链接：[https://leetcode.com/problems/integer-to-english-words/](https://leetcode.com/problems/integer-to-english-words/) Convert a non-negative integer to its english words representation. Given input is guaranteed to be less than 2^31 - 1. Example 1: ``` Input: 123 Output: "One Hundred Twenty Three" ``` Example 2: ``` Input: 12345 Output: "Twelve Thousand Three Hundred Forty Five" ``` Example 3: ``` Input: 1234567 Output: "One Million Two Hundred Thirty Four Thousand Five Hundred Sixty Seven" ``` Example 4: ``` Input: 1234567891 Output: "One Billion Two Hundred Thirty Four Million Five Hundred Sixty Seven Thousand Eight Hundred Ninety One" ``` # 分析过程 - 输入：整形 - 输出：这个整形的英语单词描述 - 思路： - 将整形拆成几个三位数，以三位数为单位进行翻译。最高支持的 Billion，所以设计三次拆分，单位以此是 Billion, Million, Thousand。剩下的问题就是如何翻译三位数了。 - 判断三位数有无百位，直接除以 100，有的话后面加 Hundred。 - 剩下的两位数如果是 0 就直接什么都不干了，以几百直接结尾就行了。 - 建立 0 ~ 20 的表，剩下的两位如果不是 0 且小于 20 的直接查表。 - 如果剩下的两位大于 20，建立十位表，查出十位，拼上。 - 继续考虑个位，如果个位是 0 就什么也不干，不是 0 就用 0 ~ 20 的表查出个位拼上。 # 解决方法 ```swift class Solution { func convertHundred(_ i: Int) -> String { let v1 = ["", "One", "Two", "Three", "Four", "Five", "Six", "Seven", "Eight", "Nine", "Ten", "Eleven", "Twelve", "Thirteen", "Fourteen", "Fifteen", "Sixteen", "Seventeen", "Eighteen", "Nineteen"] let v2 = ["", "", "Twenty", "Thirty", "Forty", "Fifty", "Sixty", "Seventy", "Eighty", "Ninety"] let h = i / 100 let t = i % 100 let g = i % 10 var result = "" result += h > 0 ? v1[h] + " Hundred ": "" result += t < 20 ? (t == 0 ? "" : (t == 0 ? "" : v1[t] + " ")) : (v2[t / 10] + " " + (g == 0 ? "" : v1[g] + " ")) return result } func numberToWords(_ num: Int) -> String { if num == 0 { return "Zero" } let v3 = ["Thousand", "Million", "Billion"] var val = num var result = convertHundred(val % 1000) for v in v3 { val /= 1000; result = val % 1000 > 0 ? convertHundred(val % 1000) + v + " " + result : result; } return String(result.dropLast()) } } ```