<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 Comp {
private:
    vector<char> chars;
    int ptr;
public:
    Comp(vector<char>& idx) {
        chars = idx;
        ptr = 0;
        build();
    }

    Comp() {
        ptr = 0;
    }

    char curr() {
        return chars[ptr++];
    }  

    void add(char c) {
        chars.push_back(c);
    } 

    void build() {
        sort(chars.begin(), chars.end());
    }
};


class Solution {
public:
    string smallestStringWithSwaps(string s, vector<vector<int>>& pairs) {
        vector<Comp*> comps(s.length());

        vector<vector<int>> adj(s.length());

        for (auto pair: pairs) {
            adj[pair[0]].push_back(pair[1]);
            adj[pair[1]].push_back(pair[0]);
        }

        vector<int> vis(s.length(), 0);


        for (int i = 0; i < s.length(); i++) {
            if (vis[i] == 0) {
                Comp* comp = new Comp();
                comps[i] = comp;
                fun(i, s, adj, vis, comps);
                comps[i]->build();
            }
        }

        string op = "";


        for (int i = 0; i < s.length(); i++) {
            op.push_back(comps[i]->curr());
        }

        return op;
    }

    void fun(int i, string& s, vector<vector<int>>& adj, vector<int>& vis, vector<Comp*>& comps) {
        vis[i] = 1;
        comps[i]->add(s[i]);

        for (auto child: adj[i]) {
            if (vis[child] == 0) {
                comps[child] = comps[i];
                fun(child, s, adj, vis, comps);
            }
        }
    }
};
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