LeetCode-in-Java

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”

Constraints:

• 0 <= n <= 231 - 1

Solution

public 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;
    }
}

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