<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<char> v;
    vector<int> u;
    void dfs(string &s,vector<vector<int>> &graph,int i,vector<int> &vis){
        if(vis[i]){
            return;
        }
        vis[i]=1;
        v.push_back(s[i]);
        u.push_back(i);
        // cout<<s[i]<<" "<<i<<endl;
        for(auto j:graph[i]){
            dfs(s,graph,j,vis);
        }
    }
    string smallestStringWithSwaps(string s, vector<vector<int>>& pairs) {
        // vector<vector<int>> v;
        int n=s.size();
        vector<int> vis(n,0);
        vector<vector<int>> graph(n);
        for(auto i:pairs){
            graph[i[0]].push_back(i[1]);
            graph[i[1]].push_back(i[0]);
        }
        // string out=s;
        for(int i=0;i<n;i++){
            if(!vis[i]){
                v.clear();
                u.clear();
                dfs(s,graph,i,vis);
            }
            sort(v.begin(),v.end());
            sort(u.begin(),u.end());
            for(int j=0;j<u.size();j++){
                // char c=v[j];
                // cout<<v[j]<<endl;
                s[u[j]]=v[j];
            }
        }
        return s;

    }
};
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