<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 WeightedUnionFind:
    def __init__(self, n: int):
        self.parent = list(range(n))
        self.group = [set([i]) for i in range(n)]

    def _root(self, node: int) -> int:
        while self.parent[node] != node:
            self.parent[node] = self.parent[self.parent[node]]
            node = self.parent[node]
        return node

    def find(self, node1, node2) -> bool:
        return self._root(node1) == self._root(node2)
    
    def union(self, node1, node2) -> None:
        root1, root2 = self._root(node1), self._root(node2)
        if len(self.group[root1]) < len(self.group[root2]):
            root1, root2 = root2, root1
        self.parent[root2] = root1
        self.parent[root2] = root1
        self.group[root1] |= self.group[root2]
class Solution(object):
    def smallestStringWithSwaps(self, s, pairs):
        uf = WeightedUnionFind((l := len(s)))
        for a, b in pairs:
            uf.union(a, b)
        res = [''] * l
        for root in [i for i, node in enumerate(uf.parent) if node == i]:
            for i, ch in zip(sorted(uf.group[root]), sorted(s[i] for i in uf.group[root])):
                res[i] = ch
        return ''.join(res)
523