1556. Thousand Separator

QUESTION:

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

EXPLANATION:

easy的题目， 直接首先反向， 然后for循环进行添加， 最后再进行反向输出即可。

SOLUTION:

class Solution {
    fun thousandSeparator(n: Int): String {
        var result: StringBuilder = StringBuilder()
        var nString = n.toString().reversed()
        for (index in nString.indices) {
            if (index != 0 && index % 3 == 0) {
                result.append(".")
            }
            result.append(nString[index])
        }
        return result.reversed().toString()
    }
}
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