Problem
Given an integer n, add a dot (".") as the thousands separator and return it in string format.
Example 1:
Input: n = 987
Output: "987"
Example 2:
Input: n = 1234
Output: "1.234"
Constraints:
0 <= n <= 2^31 - 1
Solution (Java)
class Solution {
public String thousandSeparator(int n) {
String str = Integer.toString(n);
StringBuilder sb = new StringBuilder();
int i = str.length() - 1;
int j = 1;
while (i >= 0) {
sb.append(str.charAt(i));
j++;
if (j % 3 == 0) {
sb.append(".");
}
i--;
j++;
}
String result = sb.reverse().toString();
if (result.charAt(0) == '.') {
result = result.substring(1);
}
return result;
}
}
Explain:
nope.
Complexity:
- Time complexity : O(n).
- Space complexity : O(n).