<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>

using ll = long long;
class DSU{
    public:
    vector<int> rank;
    vector<int> parent;
    int n;
    DSU(int n){
        this->n=n;
        rank=vector<int>(n,1);
        parent=vector<int>(n,0);
        iota(parent.begin(),parent.end(),0);
        
    }
    ll find(ll a){
        if(parent[a]==a) return a;
        else return parent[a]=find(parent[a]);
    }
    void unionF(ll a , ll b ){
        ll pa = find(a);
        ll pb = find(b);
        if(pa==pb) return ;
        if(rank[pa]>rank[pb]){
            swap(pa,pb);
        }
        parent[pa]=pb;
        if (rank[pa] == rank[pb])
            rank[pb]++;
    }
       

};
class Solution {
public:
    string smallestStringWithSwaps(string s, vector<vector<int>>& p) {
        DSU ds(s.size());
        for(auto i:p){
            ds.unionF(i[0],i[1]);
        }
        // priority_queue<char, vector<char>, greater<char> >
        map<int,priority_queue<char, vector<char>, greater<char>>> pq;
        for(int i=0;i<s.size();i++){
            pq[ds.find(i)].push(s[i]);
            // cout<<ds.find(i)<<"->"<<s[i]<<"  ";
        }
        // cout<<endl;


        for(int i=0;i<s.size();i++){
            int par=ds.find(i);
            s[i]=pq[par].top();
            // cout<<pq[par].top()<<"->"<<par<<"  "<<i<<"  ";
            pq[par].pop();
        }
        return s;

        
    }
};
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