2109 - Adding Spaces to a String.

Medium

You are given a 0-indexed string s and a 0-indexed integer array spaces that describes the indices in the original string where spaces will be added. Each space should be inserted before the character at the given index.

• For example, given s = "EnjoyYourCoffee" and spaces = [5, 9], we place spaces before 'Y' and 'C', which are at indices 5 and 9 respectively. Thus, we obtain "Enjoy **Y**our **C**offee".

Return the modified string after the spaces have been added.

Example 1:

Input: s = "LeetcodeHelpsMeLearn", spaces = 8,13,15

Output: "Leetcode Helps Me Learn"

Explanation:

The indices 8, 13, and 15 correspond to the underlined characters in "LeetcodeHelpsMeLearn".

We then place spaces before those characters.

Example 2:

Input: s = "icodeinpython", spaces = 1,5,7,9

Output: "i code in py thon"

Explanation:

The indices 1, 5, 7, and 9 correspond to the underlined characters in "icodeinpython".

We then place spaces before those characters.

Example 3:

Input: s = "spacing", spaces = 0,1,2,3,4,5,6

Output: " s p a c i n g"

Explanation: We are also able to place spaces before the first character of the string.

Constraints:

• <code>1 <= s.length <= 3 * 10⁵</code>

• s consists only of lowercase and uppercase English letters.

• <code>1 <= spaces.length <= 3 * 10⁵</code>

• 0 <= spaces[i] <= s.length - 1

• All the values of spaces are strictly increasing.