<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:
    vector<int> bfs(int node, string&s, vector<vector<int>>&adj, vector<int>&vis){
        vector<int>res;
        queue<int> q;
        q.push(node);
        vis[node]=1;
        
        while(!q.empty()){
            int nd = q.front();
            res.push_back(nd);
            q.pop();
            for(auto it: adj[nd]){
                if(!vis[it]){
                    vis[it]=1;  
                    q.push(it);
                }
            }
        }
        return res;


    }

    string smallestStringWithSwaps(string s, vector<vector<int>>& pairs) {
        int n = s.size();
        vector<vector<int>> adj(n);
        for(auto it: pairs){
            adj[it[0]].push_back(it[1]);
            adj[it[1]].push_back(it[0]);
        }
        vector<int> vis(n,0);
        for(int i=0; i<n; i++){
            if(!vis[i]){
                vector<int>tp = bfs(i,s,adj,vis);
                string str = "";
                for(auto it: tp){str.push_back(s[it]);}
                sort(str.begin(),str.end());
                sort(tp.begin(),tp.end());
                for(int i=0; i<str.size();i++){s[tp[i]] = str[i];}
            }
        }
        return s;


    }
};
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