<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 {
public:
    int findP(int node, vector<int>& parent)
	{
	    if(parent[node]==node)
	    {
	        return node;
	    }
	    return parent[node]=findP(parent[node], parent);
	}
	
	void unionSize (int u, int v, vector<int>& parent, vector<int>& size)
	{
	    int paru=findP(u,parent);
	    int parv=findP(v,parent);
	    if(parv==paru)
	    {
	        return;
	    }
	    if(size[paru]<size[parv])
	    {
	        parent[paru]=parv;
	        size[parv]+=size[paru];
	    }
	    else
	    {
	        parent[parv]=paru;
	        size[paru]+=size[parv];
	    }
	}
    string smallestStringWithSwaps(string s, vector<vector<int>>& pairs) {
        string ans="";
        unordered_map<int, vector<char>>m;
        int n=s.size();
        vector<int>parent(n);
        vector<int>size(n,1);
        for(int i=0;i<n;i++)
        {
            parent[i]=i;
        }
        for(int i=0;i<pairs.size();i++)
        {
            unionSize(pairs[i][0], pairs[i][1], parent, size);
        }
        for(int i=0;i<n;i++)
        {
            int par=findP(i, parent);
            m[par].push_back(s[i]);
        }
        for(auto& val:m)
        {
            sort(val.second.begin(), val.second.end(), greater<char>());
        }
        for(int i=0;i<n;i++)
        {
            int par=findP(i, parent);
            s[i]=m[par].back();
            m[par].pop_back();
        }
        return s;
    }
};
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