Leetcode

Adding Spaces to a String

  • Time:O(n)
  • Space:O(n)

C++

class Solution {
 public:
  string addSpaces(string s, vector<int>& spaces) {}
};

JAVA

class Solution {
  public String addSpaces(String s, int[] spaces) {
    StringBuilder sb = new StringBuilder();
    int j = 0; // spaces' index

    for (int i = 0; i < s.length(); ++i) {
      if (j < spaces.length && i == spaces[j]) {
        sb.append(' ');
        ++j;
      }
      sb.append(s.charAt(i));
    }

    return sb.toString();
  }
}

Python

class Solution:
  def addSpaces(self, s: str, spaces: List[int]) -> str:
    ans = []
    j = 0  # spaces' index

    for i, c in enumerate(s):
      if j < len(spaces) and i == spaces[j]:
        ans.append(' ')
        j += 1
      ans.append(c)

    return ''.join(ans)