algorithm-class/大厂刷题班/class42/Problem_0273_IntegerToEnglishWords.java

package class42;

public class Problem_0273_IntegerToEnglishWords {

	public static String num1To19(int num) {
		if (num < 1 || num > 19) {
			return "";
		}
		String[] names = { "One ", "Two ", "Three ", "Four ", "Five ", "Six ", "Seven ", "Eight ", "Nine ", "Ten ",
				"Eleven ", "Twelve ", "Thirteen ", "Fourteen ", "Fifteen ", "Sixteen ", "Seventeen", "Eighteen ",
				"Nineteen " };
		return names[num - 1];
	}

	public static String num1To99(int num) {
		if (num < 1 || num > 99) {
			return "";
		}
		if (num < 20) {
			return num1To19(num);
		}
		int high = num / 10;
		String[] tyNames = { "Twenty ", "Thirty ", "Forty ", "Fifty ", "Sixty ", "Seventy ", "Eighty ", "Ninety " };
		return tyNames[high - 2] + num1To19(num % 10);
	}

	public static String num1To999(int num) {
		if (num < 1 || num > 999) {
			return "";
		}
		if (num < 100) {
			return num1To99(num);
		}
		int high = num / 100;
		return num1To19(high) + "Hundred " + num1To99(num % 100);
	}

	public static String numberToWords(int num) {
		if (num == 0) {
			return "Zero";
		}
		String res = "";
		if (num < 0) {
			res = "Negative ";
		}
		if (num == Integer.MIN_VALUE) {
			res += "Two Billion ";
			num %= -2000000000;
		}
		num = Math.abs(num);
		int high = 1000000000;
		int highIndex = 0;
		String[] names = { "Billion ", "Million ", "Thousand ", "" };
		while (num != 0) {
			int cur = num / high;
			num %= high;
			if (cur != 0) {
				res += num1To999(cur);
				res += names[highIndex];
			}
			high /= 1000;
			highIndex++;
		}
		return res.trim();
	}

	public static void main(String[] args) {
		int test = Integer.MIN_VALUE;
		System.out.println(test);

		test = -test;
		System.out.println(test);

		int num = -10001;
		System.out.println(numberToWords(num));
	}

}