<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>

#include<bits/stdc++.h>
#define ll long long
using namespace std;

class disjoint {
    ll* parent;
    ll* size;
public:
    disjoint(ll n) {
        parent = new ll[n];
        size = new ll[n];
        for (ll i = 0; i < n; i++) {
            parent[i] = i;
            size[i] = 1;
        }
    }

    ~disjoint() {
        delete[] parent;
        delete[] size;
    }

    ll findPar(ll i) {
        if (parent[i] == i) {
            return i;
        }
        return parent[i] = findPar(parent[i]);
    }

    void unionBySize(ll x, ll y) {
        ll ulpx = findPar(x);
        ll ulpy = findPar(y);
        if(ulpx!=ulpy){
            if (size[ulpx] > size[ulpy]) {
                parent[ulpy] = ulpx;
                size[ulpx] += size[ulpy];
            }
            else {
                parent[ulpx] = ulpy;
                size[ulpy] += size[ulpx];
            }
        }
    }
};
class Solution {
public:
    string smallestStringWithSwaps(string s, vector<vector<int>>& pairs) {
        ll n=s.size();
        disjoint ds(n);
        for(auto it:pairs){
            ds.unionBySize(it[0],it[1]);
        }
        map<ll,vector<char>> mpp;
        for(ll i=0;i<n;i++){
            ll p=ds.findPar(i);
            mpp[p].push_back(s[i]);
        }
        for(auto& it:mpp){
            sort(it.second.begin(),it.second.end());
            
        }
        string ans="";
        for(ll i=0;i<n;i++){
            ll p=ds.findPar(i);
            ans+=mpp[p].front();
            mpp[p].erase(mpp[p].begin());
        }
        return ans;
    }
};
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