[LeetCode] Integer to English Words

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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”

解题思路

略。

实现代码

// Runtime: 8 msclass Solution {public:    string numberToWords(int num) {        return num2str(num);    }private:    string num2str(int num)    {        string res = "";        if (num <= 19)        {            res += nums[num];        }        else if (num <= 99)        {            res += tens[num / 10];            if (num % 10 != 0)            {                res += " ";                res += num2str(num % 10);            }        }        else if (num <= 999)        {            res += num2str(num / 100);            res += " Hundred";            if (num % 100 != 0)            {                res += " ";                res += num2str(num % 100);            }        }        else if (num <= 999999)        {            res += num2str(num / 1000);            res += " Thousand";            if (num % 1000 != 0)            {                res += " ";                res += num2str(num % 1000);            }        }        else if (num <= 999999999)        {            res += num2str(num / 1000000);            res += " Million";            if (num % 1000000 != 0)            {                res += " ";                res += num2str(num % 1000000);            }        }        else if (num <= 999999999999)        {            res += num2str(num / 1000000000);            res += " Billion";            if (num % 1000000000 != 0)            {                res += " ";                res += num2str(num % 1000000000);            }        }        return res;    }    string tens[10] = {"", "", "Twenty", "Thirty", "Forty", "Fifty", "Sixty", "Seventy", "Eighty", "Ninety"};    string nums[20] = {"Zero", "One", "Two", "Three", "Four", "Five", "Six", "Seven", "Eight",        "Nine", "Ten", "Eleven", "Twelve", "Thirteen", "Fourteen", "Fifteen", "Sixteen", "Seventeen",        "Eighteen", "Nineteen"};};

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