<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> allchar;
    vector <int> pos;
    string str;
    void dfs(int node, vector<bool>& vst, map<int, vector<int>>& adj) {
        vst[node] = true;
        allchar.push_back(str[node]);
        pos.push_back(node);
        for (auto itr : adj[node]) {
            if (!vst[itr]) {
                dfs(itr, vst, adj);
            }
        }
    }
    string smallestStringWithSwaps(string s, vector<vector<int>>& pairs) {
        map<int ,vector<int>> adj;
        for (auto itr: pairs)
        {
            adj[itr[0]].push_back(itr[1]);
            adj[itr[1]].push_back(itr[0]);
        }
        str=s;
        int n=s.length();
        vector <bool> vst(n,0);
        for (int i=0;i<n;i++)
        {
            if (!vst[i])
            {
               allchar.clear();
               pos.clear();
                dfs(i,vst,adj);
                sort(pos.begin(),pos.end());
                sort(allchar.begin(),allchar.end());
                for (int j=0;j<pos.size();j++)
                {
                    str[pos[j]]=allchar[j];
                }
               
            }
        }
        return str;
    }
};
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