Problem
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"
Constraints:
0 <= num <= 231 - 1
Solution
/**
* @param {number} num
* @return {string}
*/
var numberToWords = function(num) {
if (num === 0) return 'Zero';
var words1 = [
'One',
'Two',
'Three',
'Four',
"Five",
"Six",
'Seven',
'Eight',
'Nine',
];
var words2 = [
'Ten',
'Eleven',
'Twelve',
'Thirteen',
'Fourteen',
'Fifteen',
'Sixteen',
'Seventeen',
'Eighteen',
'Nineteen',
];
var words3 = [
'Ten',
'Twenty',
'Thirty',
'Forty',
'Fifty',
'Sixty',
'Seventy',
'Eighty',
'Ninety',
];
var getStr = function(number) {
var res = [];
var num1 = Math.floor(number / 100);
if (num1 > 0) {
res.push(`${words1[num1 - 1]} Hundred`);
}
number %= 100;
if (number >= 10 && number <= 19) {
res.push(words2[number - 10]);
} else {
var num2 = Math.floor(number / 10);
if (num2 > 0) {
res.push(words3[num2 - 1]);
}
number %= 10;
if (number > 0) {
res.push(words1[number - 1]);
}
}
return res.join(' ');
};
var res = [];
[
[Math.pow(10, 9), 'Billion'],
[Math.pow(10, 6), 'Million'],
[Math.pow(10, 3), 'Thousand'],
].forEach(item => {
var num1 = Math.floor(num / item[0]);
if (num1 > 0) {
res.push(`${getStr(num1)} ${item[1]}`);
}
num %= item[0];
});
if (num > 0) {
res.push(getStr(num));
}
return res.join(' ');
};
Explain:
nope.
Complexity:
- Time complexity : O(log(n)).
- Space complexity : O(log(n)).