Integer to English Words

Convert a non-negative integer to its english words representation. Given input is guaranteed to be less than 231 - 1.

For example,

123 -> "One Hundred Twenty Three"12345 -> "Twelve Thousand Three Hundred Forty Five"1234567 -> "One Million Two Hundred Thirty Four Thousand Five Hundred Sixty Seven"

 

 

 先把数字分割成4个三分位处理。前3个三分位分别加上Billion,Million,Thousand。

三分位处理函数为Helper()

class Solution {public:    string Helper(string numStr, string dict1[], string dict2[], string dict3[])    {        int num = atoi(numStr.c_str());        if(num == 0)            return "";        else        {            string ret = "";            int hundred = numStr[0] - '0';            int ten = numStr[1] - '0';            int one = numStr[2] - '0';                        if(hundred != 0)                ret += dict1[hundred-1] + " Hundred";            if(ten == 0)            {                if(one == 0)                    return ret;                else                    return (ret=="")?(dict1[one-1]):(ret+" "+dict1[one-1]);             }            else if(ten == 1)            {                return (ret=="")?(dict2[one]):(ret+" "+dict2[one]);             }            else            {                if(one == 0)                    return (ret=="")?(dict3[ten-2]):(ret+" "+dict3[ten-2]);                else                    return (ret=="")?(dict3[ten-2]+" "+dict1[one-1]):(ret+" "+dict3[ten-2]+" "+dict1[one-1]);            }        }    }    string numberToWords(int num) {        if(num == 0)            return "Zero";        else        {            string ret = "";            string dict1[9] = {
    "One","Two","Three","Four","Five","Six","Seven","Eight","Nine"};            string dict2[10] = {
    "Ten","Eleven","Twelve","Thirteen","Fourteen","Fifteen","Sixteen","Seventeen",                            "Eighteen","Nineteen"};            string dict3[8] = {
    "Twenty","Thirty","Forty","Fifty","Sixty","Seventy","Eighty","Ninety"};            string numStr = to_string(num);            int len = numStr.size();            string padding = string(12-len, '0');            numStr = padding + numStr;            string billionStr = Helper(numStr.substr(0,3), dict1, dict2, dict3);            if(billionStr != "")                ret += billionStr + " Billion";            string millionStr = Helper(numStr.substr(3,3), dict1, dict2, dict3);            if(millionStr != "")                ret += (ret=="")?(millionStr+" Million"):(" "+millionStr+" Million");            string thousandStr = Helper(numStr.substr(6,3), dict1, dict2, dict3);            if(thousandStr != "")                ret += (ret=="")?(thousandStr+" Thousand"):(" "+thousandStr+" Thousand");            string oneStr = Helper(numStr.substr(9,3), dict1, dict2, dict3);            if(oneStr != "")                ret += (ret=="")?(oneStr):(" "+oneStr);            return ret;        }    }};