Adding Spaces to a String
<p>You are given a <strong>0-indexed</strong> string <code>s</code> and a <strong>0-indexed</strong> integer array <code>spaces</code> that describes the indices in the original string where spaces will be added. Each space should be inserted <strong>before</strong> the character at the given index.</p>

<ul>
	<li>For example, given <code>s = &quot;EnjoyYourCoffee&quot;</code> and <code>spaces = [5, 9]</code>, we place spaces before <code>&#39;Y&#39;</code> and <code>&#39;C&#39;</code>, which are at indices <code>5</code> and <code>9</code> respectively. Thus, we obtain <code>&quot;Enjoy <strong><u>Y</u></strong>our <u><strong>C</strong></u>offee&quot;</code>.</li>
</ul>

<p>Return<strong> </strong><em>the modified string <strong>after</strong> the spaces have been added.</em></p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> s = &quot;LeetcodeHelpsMeLearn&quot;, spaces = [8,13,15]
<strong>Output:</strong> &quot;Leetcode Helps Me Learn&quot;
<strong>Explanation:</strong> 
The indices 8, 13, and 15 correspond to the underlined characters in &quot;Leetcode<u><strong>H</strong></u>elps<u><strong>M</strong></u>e<u><strong>L</strong></u>earn&quot;.
We then place spaces before those characters.
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> s = &quot;icodeinpython&quot;, spaces = [1,5,7,9]
<strong>Output:</strong> &quot;i code in py thon&quot;
<strong>Explanation:</strong>
The indices 1, 5, 7, and 9 correspond to the underlined characters in &quot;i<u><strong>c</strong></u>ode<u><strong>i</strong></u>n<u><strong>p</strong></u>y<u><strong>t</strong></u>hon&quot;.
We then place spaces before those characters.
</pre>

<p><strong class="example">Example 3:</strong></p>

<pre>
<strong>Input:</strong> s = &quot;spacing&quot;, spaces = [0,1,2,3,4,5,6]
<strong>Output:</strong> &quot; s p a c i n g&quot;
<strong>Explanation:</strong>
We are also able to place spaces before the first character of the string.
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= s.length &lt;= 3 * 10<sup>5</sup></code></li>
	<li><code>s</code> consists only of lowercase and uppercase English letters.</li>
	<li><code>1 &lt;= spaces.length &lt;= 3 * 10<sup>5</sup></code></li>
	<li><code>0 &lt;= spaces[i] &lt;= s.length - 1</code></li>
	<li>All the values of <code>spaces</code> are <strong>strictly increasing</strong>.</li>
</ul>
Array; Two Pointers; String; Simulation
function addSpaces(s: string, spaces: number[]): string {
    const ans: string[] = [];
    for (let i = 0, j = 0; i < s.length; i++) {
        if (i === spaces[j]) {
            ans.push(' ');
            j++;
        }
        ans.push(s[i]);
    }
    return ans.join('');
}
