1 题目
将人民币的数字金额转化成大写金额，例如：
input : 012000500.4
output : 壹仟贰佰万伍佰圆肆角
人民币数字金额转成大写金额是一道很老的面试题了，我就曾经遇到过，写过java和javascript的实现方法，但总是纠结于实现算法不够理想，象是算法里有好多补丁。这道题主要考察观察总结和算法的设计能力，细节和边界的处理能力等，看起来并不太难，但要很完美实现也不容易，尤其是在纸上编程，更要求思路清晰和明确。
2 算法分析
- 处理待转换的字符串，去掉开头空格，补齐结尾角分位，得到
1200050040 - 设计数字对应中文数组
{"零","壹","贰","叁","肆","伍","陆","柒","捌","玖"} - 设计中文单位数组
{"分","角","圆","拾","佰","仟","万","拾","佰","仟","亿","拾","佰","仟","万","拾","佰","仟"} - 循环input，逐位转化成中文和单位组合，得到
壹仟贰佰零拾零万零仟伍佰零拾零圆肆角零分 - 利用正则表达式，去掉零仟、零佰、零拾、零角、零分
- 利用正则表达式，替换零亿、零万、零圆、亿万 为 亿、万、圆、亿
- 以 圆 结尾，结尾加上 ** 整 ** 字
3 java实现
public static String toUpper(String num) {
String[] nums = {"零","壹","贰","叁","肆","伍","陆","柒","捌","玖"};
String[] units = {"分","角","圆","拾","佰","仟","万","拾","佰","仟","亿","拾","佰","仟","万","拾","佰","仟"};
StringBuilder result = new StringBuilder();
num = num.replaceAll("^[0]+","");
num += "00";
if(num.contains(".")) {
int index = num.indexOf(".");
num = num.substring(0,index)+ num.substring(index+1,index+3);
}
int len = num.length();
if(len > 18) {
throw new RuntimeException("数字太大，无法处理！");
}
for(int i = 0; i < len; i++) {
int c = num.charAt(i);
if(c >47 && c <58) {
result.append(nums[c - 48] + units[len - i -1]);
}
}
String str = result.toString();
str = str.replaceAll("(零仟)|(零佰)|(零拾)|(零角)|(零分)","");
str = str.replace("零亿","亿");
str = str.replace("零万","万");
str = str.replace("零圆","圆");
str = str.replace("亿万","亿");
if(str.endsWith("圆")) {
str += "整";
}
return str;
}
4 javascript实现
function toUpper(num) {
var nums = "零壹贰叁肆伍陆柒捌玖".split("");
var units = "分角圆拾佰仟万拾佰仟亿拾佰仟万拾佰仟".split("");
var result = "";
num = num.replace(/^[0]/,"");
num += "00";
var index = num.indexOf(".");
if(index > -1) {
var index = num.indexOf(".");
num = num.substring(0,index)+ num.substring(index+1,index+3);
}
var len = num.length;
for(var i = 0; i < len; i++) {
var c = num.charAt(i);
if(c >= 0 && c < 10) {
result += (nums[c] + units[len - i -1]);
}
}
result = result.replace(/零仟|零佰|零拾|零角|零分/g,"");
result = result.replace("零亿","亿");
result = result.replace("零万","万");
result = result.replace("零圆","圆");
result = result.replace("亿万","亿");
if(result.charAt(result.length-1) == '圆') {
result += "整";
}
return result;
}
5 补充
本来想写C语言的实现算法，没有时间写了，抱歉，算法经过基本的测试验证，可以最高处理千万亿级别的转换。
另外，总是觉得算法的实现还可以优化，还是本人太纠结了？大家帮助提一下建议，也可以帮忙给出C语言及其它语言的实现方法。
提供WEB版的转换小工具，供大家报销发票的时候使用。
