ZCW-Interview-Problem6/src/main/java/io/zipcoder/NumberToWords.java at 28cfb30e659b661e1cb60c4ebd9ff6ff13295906 · Zipcoder/ZCW-Interview-Problem6 · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
package io.zipcoder;

import java.text.DecimalFormat;

public class NumberToWords {

    private static final String[] tensNames = {
            "",
            " Ten",
            " Twenty",
            " Thirty",
            " Forty",
            " Fifty",
            " Sixty",
            " Seventy",
            " Eighty",
            " Ninety"
    };

    private static final String[] numNames = {
            "",
            " One",
            " Two",
            " Three",
            " Four",
            " Five",
            " Six",
            " Seven",
            " Eight",
            " Nine",
            " Ten",
            " Eleven",
            " Twelve",
            " Thirteen",
            " Fourteen",
            " Fifteen",
            " Sixteen",
            " Seventeen",
            " Eighteen",
            " Nineteen"
    };

    public NumberToWords() {}

    private static String convertLessThanOneThousand(int number) {
        String soFar;

        if (number % 100 < 20){
            soFar = numNames[number % 100];
            number /= 100;
        }
        else {
            soFar = numNames[number % 10];
            number /= 10;

            soFar = tensNames[number % 10] + soFar;
            number /= 10;
        }
        if (number == 0) return soFar;
        return numNames[number] + " Hundred" + soFar;
    }


    public static String convert(long number) {
        // 0 to 999 999 999 999
        if (number == 0) { return "Zero"; }

        String snumber = Long.toString(number);

        // pad with "0"
        String mask = "000000000000";
        DecimalFormat df = new DecimalFormat(mask);
        snumber = df.format(number);

        // XXXnnnnnnnnn
        int billions = Integer.parseInt(snumber.substring(0,3));
        // nnnXXXnnnnnn
        int millions  = Integer.parseInt(snumber.substring(3,6));
        // nnnnnnXXXnnn
        int hundredThousands = Integer.parseInt(snumber.substring(6,9));
        // nnnnnnnnnXXX
        int thousands = Integer.parseInt(snumber.substring(9,12));

        String tradBillions;
        switch (billions) {
            case 0:
                tradBillions = "";
                break;
            case 1 :
                tradBillions = convertLessThanOneThousand(billions)
                        + " billion ";
                break;
            default :
                tradBillions = convertLessThanOneThousand(billions)
                        + " billion ";
        }
        String result =  tradBillions;

        String tradMillions;
        switch (millions) {
            case 0:
                tradMillions = "";
                break;
            case 1 :
                tradMillions = convertLessThanOneThousand(millions)
                        + " million ";
                break;
            default :
                tradMillions = convertLessThanOneThousand(millions)
                        + " million ";
        }
        result =  result + tradMillions;

        String tradHundredThousands;
        switch (hundredThousands) {
            case 0:
                tradHundredThousands = "";
                break;
            case 1 :
                tradHundredThousands = "one thousand ";
                break;
            default :
                tradHundredThousands = convertLessThanOneThousand(hundredThousands)
                        + " thousand ";
        }
        result =  result + tradHundredThousands;

        String tradThousand;
        tradThousand = convertLessThanOneThousand(thousands);
        result =  result + tradThousand;

        // remove extra spaces!
        return result.replaceAll("^\\s+", "").replaceAll("\\b\\s{2,}\\b", " ");
    }
}