<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:
class dsu{
    private:
    vector<int> parent;
    vector<int> rank;
    public:
    dsu(int x){
        parent.resize(x);
        rank.resize(x);
        for(int i =0; i < x;i++){
            parent[i] = i;
            rank[i] = 1;
        }
    }
    bool connect(int x, int y){
        int p1 = find(x);
        int p2 = find(y);
        if(p1 != p2){
            if(rank[p1] > rank[p2]){
                parent[p2] = p1;
            } else if(rank[p2] > rank[p1]){
                parent[p1] = p2;
            } else{
                parent[p2] = p1;
                rank[p1]++;
            }
            return true;
        }
        return false;
    }
    int find(int x){
        if(x != parent[x]) parent[x] = find(parent[x]);
        return parent[x];
    }
};
    string smallestStringWithSwaps(string s, vector<vector<int>>& pairs) {
        dsu DS(s.size());
        for(auto & pair : pairs){
            DS.connect(pair[0], pair[1]);
        }
        unordered_map<int, vector<int>> adjList;
        for(int i =0; i < s.size(); i++){
            adjList[DS.find(i)].push_back(i);
        }
        for(auto g : adjList){
            vector<char> chars;
            for(int ind : g.second){
                chars.push_back(s[ind]);
            }
            sort(chars.begin(), chars.end());
            sort(g.second.begin(), g.second.end());

            for(int i =0; i < g.second.size(); i++){
                s[g.second[i]] = chars[i];
            }
        }
        return s;
    }
};
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