<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 {

private:

    void dfs(int i, string& s, vector<vector<int>>& adj, int color, vector<bool>& visited, auto& m1, auto& m2){
        if(visited[i]) return;
        visited[i] = true;
        m1[color].push(s[i]);
        m2[color].push(i);

        for(int u : adj[i]){
            dfs(u, s, adj, color, visited, m1, m2);
        }
    }

public:
    string smallestStringWithSwaps(string s, vector<vector<int>>& pairs) {
        int n = s.length();
        vector<bool> visited(n, false);
        vector<vector<int>> adj(n);

        for(vector<int>& pair : pairs){
            int a = pair[0];
            int b = pair[1];
            adj[a].push_back(b);
            adj[b].push_back(a);
        }

        int cc = 1;
        unordered_map<int, priority_queue<char, vector<char>, greater<char>>> m1;
        unordered_map<int, priority_queue<int, vector<int>, greater<int>>> m2;

        for(int i = 0 ; i < n; i++){
            dfs(i, s, adj, cc, visited, m1, m2);
            cc++;
        }

        for(auto& e : m1){
            auto &p1 = e.second;
            auto &p2 = m2[e.first];

            while(!p1.empty()) {
                char c = p1.top();
                int idx = p2.top();
                s[idx] = c;
                p1.pop();
                p2.pop();
            }
        }


        return s;
    }
};
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