# https://leetcode.com/problems/adding-spaces-to-a-string
from typing import List

class Solution:
    def addSpaces(self, s: str, spaces: List[int]) -> str:
        result = []
        last_index = 0
        for index in spaces:
            result.append(s[last_index:index])
            result.append(" ")
            last_index = index
        result.append(s[last_index:len(s)])
        return "".join(result)