Longest Common Prefix
<p>Write a function to find the longest common prefix string amongst an array of strings.</p>

<p>If there is no common prefix, return an empty string <code>&quot;&quot;</code>.</p>

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

<pre>
<strong>Input:</strong> strs = [&quot;flower&quot;,&quot;flow&quot;,&quot;flight&quot;]
<strong>Output:</strong> &quot;fl&quot;
</pre>

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

<pre>
<strong>Input:</strong> strs = [&quot;dog&quot;,&quot;racecar&quot;,&quot;car&quot;]
<strong>Output:</strong> &quot;&quot;
<strong>Explanation:</strong> There is no common prefix among the input strings.
</pre>

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

<ul>
	<li><code>1 &lt;= strs.length &lt;= 200</code></li>
	<li><code>0 &lt;= strs[i].length &lt;= 200</code></li>
	<li><code>strs[i]</code> consists of only lowercase English letters if it is non-empty.</li>
</ul>
Trie; Array; String
# @param {String[]} strs
# @return {String}
def longest_common_prefix(strs)
  return '' if strs.nil? || strs.length.zero?

  return strs[0] if strs.length == 1

  idx = 0
  while idx < strs[0].length
    cur_char = strs[0][idx]

    str_idx = 1
    while str_idx < strs.length
      return idx > 0 ? strs[0][0..idx-1] : '' if strs[str_idx].length <= idx

      return '' if strs[str_idx][idx] != cur_char && idx.zero?
      return strs[0][0..idx - 1] if strs[str_idx][idx] != cur_char
      str_idx += 1
    end

    idx += 1
  end

  idx > 0 ? strs[0][0..idx] : ''
end
