273. Integer to English Words
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"
这道题为了省去条件判断,可以构造两个向量,将下标和英文对应,这样可以省去大量条件判断。
vector<string> unit={"","One","Two","Three","Four","Five","Six","Seven","Eight","Nine","Ten","Eleven","Twelve","Thirteen","Fourteen","Fifteen","Sixteen","Seventeen","Eighteen","Nineteen"};
vector<string> tenty = {"","","Twenty","Thirty","Forty","Fifty","Sixty","Seventy","Eighty","Ninety"};
需要添加后缀就只是billion,million,thousand,hundred;
因为每3位可以可以看作是1000以内的数,所以可以用递归做;
另外需要特别注意的是整百,整千,整百万,整十亿的数后缀没有空格,所以需要加个判断;
class Solution {
public:
string numberToWords(int num)
{
string s="";
vector<string> unit={"","One","Two","Three","Four","Five","Six","Seven","Eight","Nine","Ten","Eleven","Twelve","Thirteen","Fourteen","Fifteen","Sixteen","Seventeen","Eighteen","Nineteen"};
vector<string> tenty = {"","","Twenty","Thirty","Forty","Fifty","Sixty","Seventy","Eighty","Ninety"};
if(num==0) s+="Zero";
if(num<20) s+=unit[num];
else if(num<100)
{
if(num%10 != 0) s += tenty[num/10] + " " + unit[num%10];
else s+= tenty[num/10];
}
else if(num<1000)
{
if(num%100 != 0) s += unit[num/100] + " Hundred " + numberToWords(num%100);
else s += unit[num/100] + " Hundred";
}
else if(num<1000000)
{
if(num%1000 != 0) s += numberToWords(num/1000) + " Thousand " + numberToWords(num%1000);
else s += numberToWords(num/1000) + " Thousand";
}
else if(num<1000000000)
{
if(num%1000000 != 0) s += numberToWords(num/1000000) + " Million " + numberToWords(num%1000000);
else s += numberToWords(num/1000000) + " Million";
}
else
{
if(num%1000000000 != 0)s += numberToWords(num/1000000000) + " Billion " + numberToWords(num%1000000000);
else s += numberToWords(num/1000000000) + " Billion";
}
return s;
}
};