[LeetCode] 273. Integer to English Words

最新推荐文章于 2024-07-30 07:35:52 发布

Ber03

最新推荐文章于 2024-07-30 07:35:52 发布

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分类专栏： LeetCode String 文章标签： LeetCode String

本文链接：https://blog.youkuaiyun.com/Bertram03/article/details/101521211

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本文介绍了一种将非负整数转换为英文单词表示的方法，适用于小于2^31-1的整数。通过将数字分解为每三位一组，并分别处理百位数和其他位数，实现了从个位到十亿级别的数字转换。

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

1. Description

Convert a non-negative integer to its english words representation. Given input is guaranteed to be less than 231 - 1.

Example 1:

Input: 123
Output: "One Hundred Twenty Three"

Example 2:

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

Example 3:

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

Example 4:

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

2. Solution

My Solution is as same as the LeetCode official Solution: https://leetcode.com/problems/integer-to-english-words/solution/

We need to split the number by 3-digits parts. Every 3-digits parts split by two parts: the digit of hundred and the rest.
The numbers between 11 and 20 need to be considered separately.

It is an easy but quite sticky problem. Be careful, good luck!
code

class Solution {
    public String numberToWords(int num) {
        //First，check if num is zero
        if(num == 0){
            return "Zero";
        }
        //simplify the problem:
        //split the Interger , every parts has 3 digits
        //subproblem: convert 3 digits integer to English words.
        
        int billion = num / 1000000000;
        int million = (num - (billion * 1000000000) ) / 1000000;
        int thousand= (num - (billion * 1000000000) -(million * 1000000) ) / 1000;
        int ones = num - (billion * 1000000000) - (million * 1000000) - (thousand * 1000);

        String ans = "";
        if(billion != 0){
            ans += threedigits(billion) + " Billion";
        }
        if(million != 0){
            if( !ans.isEmpty() ){
                ans += " ";
            }
            ans += threedigits(million) + " Million";
        }
        if(thousand != 0){
            if( !ans.isEmpty() ){
                ans += " ";
            }
            ans += threedigits(thousand) + " Thousand";
        }
        if(ones != 0){
            if( !ans.isEmpty() ){
                ans += " ";
            }
            ans += threedigits(ones);
        }
        return ans;
    }
    
    // n>100 -> oneDigit(n/100) , twoDigit(n%100)
    // n%100 == 0 -> oneDigit(n/100)
    // n<100 -> twoDigit(n%100)
    public String threedigits(int n){
        int hundred = n/100;
        int rest = n%100;
        String s = "";
        if(hundred != 0 && rest != 0){
            return s + oneDigit(hundred)+" Hundred "+twoDigit(rest);
        }else if(hundred != 0 && rest ==0){
            return s + oneDigit(hundred)+" Hundred";
        }else{
            return twoDigit(rest);
        }
    }
    
    //11-19 -> betweenTenTwenty(n)
    //21-99 -> tenDigit(n%10) , oneDigit(n/10)
    //the digits of one is 0 -> ten(n)
    public String twoDigit(int n){
        int ten = n/10;
        int one = n%10;
        if(ten == 0){
            return oneDigit(one);
        }else{
            if(one == 0){
                return ten(ten);
            }else{
                return ten == 1 ? betweenTenTwenty(n) : ( ten(ten) + " " + oneDigit(one));
            }
        }
    }
    
    //n less than ten
    //from 1 to 9
    public String oneDigit(int n){
        if(n == 1){
            return "One";
        }else if(n ==2){
            return "Two";
        }else if(n ==3){
            return "Three";
        }else if(n ==4){
            return "Four";
        }else if(n ==5){
            return "Five";
        }else if(n ==6){
            return "Six";
        }else if(n ==7){
            return "Seven";
        }else if(n ==8){
            return "Eight";
        }else if(n ==9){
            return "Nine";
        }else{
            return "";
        }
    }
    
    //n is divisible by 10
    public String ten(int n){
        if(n == 1){
            return "Ten";
        }else if (n ==2){
            return "Twenty";
        }else if (n ==3){
            return "Thirty";
        }else if (n ==4){
            return "Forty";
        }else if (n ==5){
            return "Fifty";
        }else if (n ==6){
            return "Sixty";
        }else if (n ==7){
            return "Seventy";
        }else if (n ==8){
            return "Eighty";
        }else if (n ==9){
            return "Ninety";
        }else{
            return "";
        }
    }
    
    //11-19
    public String betweenTenTwenty(int n){
        if(n == 11){
            return "Eleven";
        }else if(n == 12){
            return "Twelve";
        }else if(n == 13){
            return "Thirteen";
        }else if(n == 14){
            return "Fourteen";
        }else if(n == 15){
            return "Fifteen";
        }else if(n == 16){
            return "Sixteen";
        }else if(n == 17){
            return "Seventeen";
        }else if(n == 18){
            return "Eighteen";
        }else if(n == 19){
            return "Nineteen";
        }else {
            return "";
        }
    }
}