<p>You are given a string <code>s</code>, and an array of pairs of indices in the string&nbsp;<code>pairs</code>&nbsp;where&nbsp;<code>pairs[i] =&nbsp;[a, b]</code>&nbsp;indicates 2 indices(0-indexed) of the string.</p>

<p>You can&nbsp;swap the characters at any pair of indices in the given&nbsp;<code>pairs</code>&nbsp;<strong>any number of times</strong>.</p>

<p>Return the&nbsp;lexicographically smallest string that <code>s</code>&nbsp;can be changed to after using the swaps.</p>

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

<pre>
<strong>Input:</strong> s = &quot;dcab&quot;, pairs = [[0,3],[1,2]]
<strong>Output:</strong> &quot;bacd&quot;
<strong>Explaination:</strong> 
Swap s[0] and s[3], s = &quot;bcad&quot;
Swap s[1] and s[2], s = &quot;bacd&quot;
</pre>

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

<pre>
<strong>Input:</strong> s = &quot;dcab&quot;, pairs = [[0,3],[1,2],[0,2]]
<strong>Output:</strong> &quot;abcd&quot;
<strong>Explaination: </strong>
Swap s[0] and s[3], s = &quot;bcad&quot;
Swap s[0] and s[2], s = &quot;acbd&quot;
Swap s[1] and s[2], s = &quot;abcd&quot;</pre>

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

<pre>
<strong>Input:</strong> s = &quot;cba&quot;, pairs = [[0,1],[1,2]]
<strong>Output:</strong> &quot;abc&quot;
<strong>Explaination: </strong>
Swap s[0] and s[1], s = &quot;bca&quot;
Swap s[1] and s[2], s = &quot;bac&quot;
Swap s[0] and s[1], s = &quot;abc&quot;
</pre>

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

<ul>
	<li><code>1 &lt;= s.length &lt;= 10^5</code></li>
	<li><code>0 &lt;= pairs.length &lt;= 10^5</code></li>
	<li><code>0 &lt;= pairs[i][0], pairs[i][1] &lt;&nbsp;s.length</code></li>
	<li><code>s</code>&nbsp;only contains lower case English letters.</li>
</ul>

class Solution:
    def smallestStringWithSwaps(self, s: str, pairs: List[List[int]]) -> str:
        uf = UnionFind(len(s))
        for pair in pairs:
            uf.union(pair[0], pair[1])

        groups = collections.defaultdict(lambda: ([], []))
        for idx, ch in enumerate(s):
            parent = uf.find(idx)
            groups[parent][0].append(idx)
            groups[parent][1].append(ch)

        smallestString = [''] * len(s)
        for indexes, chars in groups.values():
            indexes.sort()
            chars.sort()
            for idx, ch in zip(indexes, chars):
                smallestString[idx] = ch

        return "".join(smallestString)

class UnionFind:
    def __init__(self, n):
        self.parents = {}
        self.ranks = {}
        for i in range(n):
            self.add(i)
    
    def add(self, node):
        self.parents[node] = node
        self.ranks[node] = 0
    
    def find(self, node):
        if node != self.parents[node]:
            self.parents[node] = self.find(self.parents[node])
        
        return self.parents[node]
    
    def union(self, node1, node2):
        parent1 = self.find(node1)
        parent2 = self.find(node2)
        if parent1 != parent2:
            if self.ranks[parent1] > self.ranks[parent2]:
                self.parents[parent2] = parent1
            elif self.ranks[parent2] > self.ranks[parent1]:
                self.parents[parent1] = parent2
            else:
                self.parents[parent2] = parent1
                self.ranks[parent1] += 1

59725