<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:
    vector<int> adj[100001];
    bool visited[100001];

    string smallestStringWithSwaps(string s, vector<vector<int>>& pairs) {
        int n = s.size();
        for(int i=0; i<pairs.size(); i++) {
            int a = pairs[i][0];
            int b = pairs[i][1];
            adj[a].push_back(b);
            adj[b].push_back(a);
        }

        vector<vector<int>> connected;

        for(int i=0; i<n; i++) {
            if(visited[i]) continue;
            vector<int> component;
            queue<int> q;
            q.push(i);
            while(!q.empty()) {
                int cur = q.front(); q.pop();
                visited[cur] = true;
                component.push_back(cur);
                for(int next : adj[cur]) {
                    if(!visited[next]) {
                        q.push(next);
                        visited[next] = true;
                    }
                }
            }
            connected.push_back(component);
        }

        unordered_map<int, char> map;

        for(int i=0; i<connected.size(); i++) {
            vector<int> component = connected[i];
            string curString;
            for(int index : component) {
                curString += s[index];
            }
            sort(curString.begin(), curString.end());
            sort(component.begin(), component.end());
            for(int j=0; j<component.size(); j++) {
                map[component[j]] = curString[j];
            }
        }

        string ans;
        for(int i=0; i<n; i++) {
            if(map[i])
                ans += map[i];
            else
                ans += s[i];
        }
        return ans;
    }
};
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