Thousand Separator — LeetCode 1556 Python Solution

The problem

Given an integer n, add a dot (".") as the thousands separator and return it in string format.

Example

Input

n = 987

Output

"987"

Python solution

class Solution:
    def thousandSeparator(self, n: int) -> str:
        cnt = 0
        ans = []
        while 1:
            n, v = divmod(n, 10)
            ans.append(str(v))
            cnt += 1
            if n == 0:
                break
            if cnt == 3:
                ans.append('.')
                cnt = 0
        return ''.join(ans[::-1])

Complexity

Pattern: Hash Map

Trade memory for time: remember what you have seen so the second pass never happens. LeetCode 1556. Thousand Separator is filed here because the reference solution below belongs to the algorithm family this hub collects, even though its LeetCode tags point elsewhere.

The hash map guide has the Python template for the pattern and the 709 LeetCode problems that use it.

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