# 整数转换英文表示
将非负整数 num 转换为其对应的英文表示。
示例 1：
输入：num = 123
输出："One Hundred Twenty Three"
示例 2：
输入：num = 12345
输出："Twelve Thousand Three Hundred Forty Five"
示例 3：
输入：num = 1234567
输出："One Million Two Hundred Thirty Four Thousand Five Hundred Sixty Seven"
示例 4：
输入：num = 1234567891
输出："One Billion Two Hundred Thirty Four Million Five Hundred Sixty Seven Thousand Eight Hundred Ninety One"
提示：
## template
```java
class Solution {
String[] withinTwentyNum = new String[] { "Zero", "One", "Two", "Three", "Four", "Five", "Six", "Seven", "Eight",
"Nine", "Ten",
"Eleven", "Twelve", "Thirteen", "Fourteen", "Fifteen", "Sixteen", "Seventeen", "Eighteen", "Nineteen" };
String[] theWholeTen = new String[] { "", "", "Twenty", "Thirty", "Forty", "Fifty", "Sixty", "Seventy", "Eighty",
"Ninety" };
String[] unit = new String[] { "", "Thousand", "Million", "Billion" };
public String numberToWords(int num) {
if (num == 0) {
return withinTwentyNum[num];
}
StringBuilder sb = new StringBuilder();
int unitCount = 0;
int temp;
String[] words = new String[32];
int wordIndex = 0;
for (int n = num; num > 0; unitCount++) {
n = num % 1000;
num /= 1000;
if (n == 0) {
continue;
}
words[wordIndex++] = unit[unitCount];
temp = n % 100;
if (n % 100 > 0) {
if (temp >= 20) {
if (temp % 10 > 0) {
words[wordIndex++] = withinTwentyNum[temp % 10];
}
words[wordIndex++] = theWholeTen[temp / 10];
} else {
words[wordIndex++] = withinTwentyNum[temp];
}
}
temp = n / 100;
if (temp > 0) {
words[wordIndex++] = "Hundred";
words[wordIndex++] = withinTwentyNum[temp];
}
}
for (int index = wordIndex - 1; index >= 0; index--) {
sb.append(words[index]).append(" ");
}
return sb.toString().trim();
}
}
```
## 答案
```java
```
## 选项
### A
```java
```
### B
```java
```
### C
```java
```