Given an integer, return its base 7 string representation.
Example 1:
Input: 100
Output: "202"
Example 2:
Input: -7
Output: "-10"
Solution:
public class Solution {
public String convertToBase7(int num) {
StringBuilder sb = new StringBuilder();
boolean flag = true; // 标记num 符号
if (num == 0){
return "0";
}
if(num < 0) {
flag = false;
}
while (num != 0) {
sb.append(Math.abs(num) % 7);
num = num / 7;
}
if (!flag) {
return "-" + sb.reverse().toString();
}
return sb.reverse().toString();
}
}