Formatted question description: https://leetcode.ca/all/1556.html
1556. Thousand Separator (Easy)
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"
Example 3:
Input: n = 123456789 Output: "123.456.789"
Example 4:
Input: n = 0 Output: "0"
Constraints:
0 <= n < 2^31
Related Topics:
String
Solution 1.
// OJ: https://leetcode.com/problems/thousand-separator/
// Time: O(N)
// Space: O(1)
class Solution {
public:
string thousandSeparator(int n) {
if (n == 0) return "0";
int d = 0;
string ans;
while (n) {
ans += '0' + n % 10;
n /= 10;
if (++d % 3 == 0 && n) ans += '.';
}
reverse(begin(ans), end(ans));
return ans;
}
};
Java
class Solution {
public String thousandSeparator(int n) {
StringBuffer sb = new StringBuffer(String.valueOf(n));
for (int i = sb.length() - 3; i > 0; i -= 3)
sb.insert(i, '.');
return sb.toString();
}
}