leetcode 273. 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"

这题纯粹考细心，其他没什么说的

const string onedigit[9] = { "One", "Two", "Three", "Four", "Five", "Six", "Seven", "Eight", "Nine" };const string teensless20[10] = { "Ten", "Eleven", "Twelve", "Thirteen", "Fourteen", "Fifteen", "Sixteen", "Seventeen", "Eighteen", "Nineteen" };const string teens[8] = { "Twenty", "Thirty", "Forty", "Fifty", "Sixty", "Seventy", "Eighty", "Ninety" };class Solution {string get_digit(int num){return onedigit[num-1];}string get_teens(int num){if (num < 20)return teensless20[num - 10];return teens[num / 10 - 2];}string get_hundred(int num){string re;if (num >= 100)re += get_digit(num / 100) + " Hundred ";if (num - num / 100 * 100>=10)re +=get_teens(num - num / 100 * 100)+" ";if (num % 10 != 0 && (num - num / 100 * 100 >= 20 || num - num / 100 * 100<10))re += get_digit(num % 10);while (re.back() == ' ')re.pop_back();return re;}public:string numberToWords(int num) {//0-2 147 483 647if (num == 0)return "Zero";string re;vector<int>digits;while (num != 0){digits.push_back(num % 10);num /= 10;}if (digits.size() > 9)re += get_digit(digits[9])+" Billion ";if (digits.size() > 6){int jmax = digits.size() >= 9 ? 8 : digits.size()-1;int sum = 0;for (int j = jmax; j >= 6; j--)sum = 10 * sum + digits[j];if (sum>0)re += get_hundred(sum)+" Million ";}if (digits.size() > 3){int jmax = digits.size() >= 6 ? 5 : digits.size()-1;int sum = 0;for (int j = jmax; j >= 3; j--)sum = 10 * sum + digits[j];if (sum>0)re += get_hundred(sum) + " Thousand ";}int jmax = digits.size() >= 3 ? 2 : digits.size()-1;int sum = 0;for (int j = jmax; j >= 0; j--)sum = 10 * sum + digits[j];if (sum>0)re += get_hundred(sum);while (re.back() == ' ')re.pop_back();return re;}};

accepted

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