<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:
    string smallestStringWithSwaps(string s, vector<vector<int>>& pairs) {
        int n=s.size();
        vector<vector<int>> a(n);

        for(auto i:pairs)
        {
            a[i[0]].push_back(i[1]);
            a[i[1]].push_back(i[0]);
        }

        for(int i=0;i<n;i++)
        {
            cout<<i<<"->";
            for(auto j:a[i])
            {
                cout<<j<<" ";
            }
            cout<<endl;
        }
        vector<int> vis(n,0);
        for(int i=0;i<n;i++)
        {
            if(vis[i]==1||a[i].size()==0) continue;
            stack<int> st;
            string s1="";
            // s1+=s[i];
            // cout<<s1<<" "<<i<<endl;
            set<int> index;
            st.push(i);
            while(!st.empty())
            {
                int i1=st.top();
                // cout<<i1<<endl;
                st.pop();
                if(vis[i1]==1) continue;
                s1+=s[i1];
                index.insert(i1);
                vis[i1]=1;
                for(auto j:a[i1])
                {
                    st.push(j);
                }
                
            }
            sort(s1.begin(),s1.end());
            cout<<s1<<endl;
            int i1=0;
            for(auto j:index)
            {
                s[j]=s1[i1++];
            }
        }
        return s;
    }
};
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