# [LeetCode] 273. Integer to English Words 整数转为英文单词

Convert a non-negative integer num to its English words representation.

Example 1:

Input: num = 123
Output: "One Hundred Twenty Three"


Example 2:

Input: num = 12345
Output: "Twelve Thousand Three Hundred Forty Five"


Example 3:

Input: num = 1234567
Output: "One Million Two Hundred Thirty Four Thousand Five Hundred Sixty Seven"


Example 4:

Input: num = 1234567891
Output: "One Billion Two Hundred Thirty Four Million Five Hundred Sixty Seven Thousand Eight Hundred Ninety One"


Constraints:

• 0 <= num <= 2^31 - 1

class Solution {
public:
string numberToWords(int num) {
string res = convertHundred(num % 1000);
vector<string> v = {"Thousand", "Million", "Billion"};
for (int i = 0; i < 3; ++i) {
num /= 1000;
res = num % 1000 ? convertHundred(num % 1000) + " " + v[i] + " " + res : res;
}
while (res.back() == ' ') res.pop_back();
return res.empty() ? "Zero" : res;
}
string convertHundred(int num) {
vector<string> v1 = {"", "One", "Two", "Three", "Four", "Five", "Six", "Seven", "Eight", "Nine", "Ten", "Eleven", "Twelve", "Thirteen", "Fourteen", "Fifteen", "Sixteen", "Seventeen", "Eighteen", "Nineteen"};
vector<string> v2 = {"", "", "Twenty", "Thirty", "Forty", "Fifty", "Sixty", "Seventy", "Eighty", "Ninety"};
string res;
int a = num / 100, b = num % 100, c = num % 10;
res = b < 20 ? v1[b] : v2[b / 10] + (c ? " " + v1[c] : "");
if (a > 0) res = v1[a] + " Hundred" + (b ? " " + res : "");
return res;
}
};

Github 同步地址：

https://github.com/grandyang/leetcode/issues/273

Integer to Roman

https://leetcode.com/problems/integer-to-english-words/

https://leetcode.com/problems/integer-to-english-words/discuss/70627/Short-clean-Java-solution

https://leetcode.com/problems/integer-to-english-words/discuss/70625/My-clean-Java-solution-very-easy-to-understand

LeetCode All in One 题目讲解汇总(持续更新中...)

posted @ 2015-08-31 12:18  Grandyang  阅读(16358)  评论(6编辑  收藏  举报