<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:
    typedef unordered_map<int, vector<int>> GRAPH;
    GRAPH graph;
    vector<bool> visited;

    void addEdge(int u, int v) {
        graph[u].push_back(v);
        graph[v].push_back(u);
    }

    void dfs(int node, vector<int>& indices, vector<char>& chars, string& s) {
        visited[node] = true;
        indices.push_back(node);
        chars.push_back(s[node]);
        for (int neighbor : graph[node]) {
            if (!visited[neighbor]) {
                dfs(neighbor, indices, chars, s);
            }
        }
    }

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

        // Build the graph
        for (const auto& pair : pairs) {
            addEdge(pair[0], pair[1]);
        }

        // Process each connected component
        for (int i = 0; i < length; ++i) {
            if (!visited[i]) {
                vector<int> indices;
                vector<char> chars;
                dfs(i, indices, chars, s);

                // Sort the characters and indices
                sort(indices.begin(), indices.end());
                sort(chars.begin(), chars.end());

                // Place sorted characters back into the string
                for (int j = 0; j < indices.size(); ++j) {
                    s[indices[j]] = chars[j];
                }
            }
        }

        return s;
    }
};


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