<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 DSU{
public:
    vector<int>parent;
    vector<int>size;
    DSU(int n){
        parent.resize(n);
        size.resize(n,1);
        for(int i=0;i<n;i++)
            parent[i]=i;
    }
    int find(int u){
        if(u==parent[u])
            return u;
        return parent[u]=find(parent[u]);
    }
    void unite(int u,int v){
        int pu = find(u);
        int pv =find(v);
        if(pu==pv)
            return;
        if(pu<pv){
            parent[pv]=pu;
            size[pu]+=size[pv];
        }
        else
        {
            parent[pu]=pv;
            size[pv]+=size[pu];
        }
    }
};

class Solution {
public:
    string smallestStringWithSwaps(string s, vector<vector<int>>& pairs) {
        int n =s.length();
        DSU ds(n);
        for(int i=0;i<pairs.size();i++)
            ds.unite(pairs[i][0],pairs[i][1]);
        map<int,vector<int>>mp;
        for(int i=0;i<n;i++){
            int p =ds.find(i);
            // if(p==i)
            //     continue;
            mp[p].push_back(i);
        }
        for(auto it:mp){
            multiset<int>st;
            // st.insert(it.first);
            for(auto itt:it.second){
                // cout<<itt<<" ";
                st.insert(s[itt]);
            }
            auto x=st.begin();
            for(auto itt:it.second)
            {
                s[itt]=*x;
                x++;
            }
            st.clear();
            // cout<<endl;
        }
        return s;
    }
};
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