LeetCode-in-Java
273. Integer to English Words
Hard
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 <= 231 - 1
Solution
import java.util.StringJoiner;
public class Solution {
private String[] ones = {
"One ", "Two ", "Three ", "Four ", "Five ", "Six ", "Seven ", "Eight ", "Nine "
};
private String[] teens = {
"Ten ",
"Eleven ",
"Twelve ",
"Thirteen ",
"Fourteen ",
"Fifteen ",
"Sixteen ",
"Seventeen ",
"Eighteen ",
"Nineteen "
};
private String[] twenties = {
"Twenty ", "Thirty ", "Forty ", "Fifty ", "Sixty ", "Seventy ", "Eighty ", "Ninety "
};
public String numberToWords(int num) {
if (num == 0) {
return "Zero";
}
StringJoiner joiner = new StringJoiner("");
processThreeDigits(joiner, num / 1_000_000_000, "Billion ");
processThreeDigits(joiner, num / 1_000_000, "Million ");
processThreeDigits(joiner, num / 1_000, "Thousand ");
processThreeDigits(joiner, num, null);
return joiner.toString().trim();
}
private void processThreeDigits(StringJoiner joiner, int input, String name) {
int threeDigit = input % 1000;
if (threeDigit > 0) {
if (threeDigit / 100 > 0) {
joiner.add(ones[threeDigit / 100 - 1]);
String hundred = "Hundred ";
joiner.add(hundred);
}
if (threeDigit % 100 >= 20) {
joiner.add(twenties[(threeDigit % 100) / 10 - 2]);
if (threeDigit % 10 > 0) {
joiner.add(ones[threeDigit % 10 - 1]);
}
} else if (threeDigit % 100 >= 10 && threeDigit % 100 < 20) {
joiner.add(teens[threeDigit % 10]);
} else if (threeDigit % 100 > 0 && threeDigit % 100 < 10) {
joiner.add(ones[threeDigit % 10 - 1]);
}
if (name != null) {
joiner.add(name);
}
}
}
}