标签：
1、题目名称
Integer to English Words（按英语读法输出数字对应单词）
2、题目地址
https://leetcode.com/problems/integer-to-english-words/
3、题目内容
英文：Convert a non-negative integer to its english words representation. Given input is guaranteed to be less than 231 - 1.
中文：给出一个非负整数，输出该数字在英语对应的单词，数字小于2^31-1
例如：下面是三个转换的例子
123 -> "One Hundred Twenty Three" 12345 -> "Twelve Thousand Three Hundred Forty Five" 1234567 -> "One Million Two Hundred Thirty Four Thousand Five Hundred Sixty Seven"
4、解题方法
其实一开始我把题目想复杂了。这道题不用考虑英语中隔位要写“And”的情况。如101，在英语中的念法为“One Hundred And One”，在这道题中，只需要输出“One Hundred One”。因此，要AC本题只需要将对应位置的数字和数位写对就可以了。Java代码如下：
/**
* @功能说明：LeetCode 273 - Integer to English Words
* @开发人员：Tsybius2014
* @开发时间：2015年10月12日
*/
public class Solution {
/**
* 按英语读法输出阿拉伯数字对应单词
* @param num 数字，范围：[0,2^31-1]
* @return
*/
public String numberToWords(int num) {
if (num < 0) {
return "";
}
//数字为0直接返回
if (num == 0) {
return "Zero";
}
//左起段落
int segment1 = num / 1000000000; //段落1：十亿位-千亿位
int segment2 = num % 1000000000 / 1000000; //段落2：百万位-亿位
int segment3 = num % 1000000 / 1000; //段落3：千位-十万位
int segment4 = num % 1000; //段落4：个位-百位
String result = "";
if (segment1 > 0) {
result += numToWordsLessThan1000(segment1) + " " + "Billion";
}
if (segment2 > 0) {
result += numToWordsLessThan1000(segment2) + " " + "Million";
}
if (segment3 > 0) {
result += numToWordsLessThan1000(segment3) + " " + "Thousand";
}
if (segment4 > 0) {
result += numToWordsLessThan1000(segment4);
}
return result.trim();
}
/**
* 按英语读法输出阿拉伯数字对应单词
* @param num 数字，范围：(0,1000)
* @return
*/
private String numToWordsLessThan1000(int num) {
if (num == 0 || num >= 1000) {
return "";
}
String result = "";
if (num >= 100) {
result += numToWordsBase(num / 100) + " " + "Hundred";
}
num = num % 100;
if (num > 20) {
result += numToWordsBase(num / 10 * 10);
if (num % 10 != 0) {
result += numToWordsBase(num % 10);
}
} else if (num > 0) {
result += numToWordsBase(num);
}
return result;
}
/**
* 按英语读法输出阿拉伯数字对应单词
* @param num 数字，范围：(0,20)∪{30,40,50,60,70,80,90}
* @return
*/
private String numToWordsBase(int num) {
String result = " ";
switch (num) {
case 1: result += "One"; break;
case 2: result += "Two"; break;
case 3: result += "Three"; break;
case 4: result += "Four"; break;
case 5: result += "Five"; break;
case 6: result += "Six"; break;
case 7: result += "Seven"; break;
case 8: result += "Eight"; break;
case 9: result += "Nine"; break;
case 10: result += "Ten"; break;
case 11: result += "Eleven"; break;
case 12: result += "Twelve"; break;
case 13: result += "Thirteen"; break;
case 14: result += "Fourteen"; break;
case 15: result += "Fifteen"; break;
case 16: result += "Sixteen"; break;
case 17: result += "Seventeen"; break;
case 18: result += "Eighteen"; break;
case 19: result += "Nineteen"; break;
case 20: result += "Twenty"; break;
case 30: result += "Thirty"; break;
case 40: result += "Forty"; break;
case 50: result += "Fifty"; break;
case 60: result += "Sixty"; break;
case 70: result += "Seventy"; break;
case 80: result += "Eighty"; break;
case 90: result += "Ninety"; break;
}
return result;
}
}
END
LeetCode：Integer to English Words - 按英语读法输出数字对应单词
标签：
原文地址：http://my.oschina.net/Tsybius2014/blog/516047
