<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 UnionFind {
public:
    UnionFind(const int size) : ranks_(size), parents_(size) {
        std::iota(parents_.begin(), parents_.end(), 0);
    }

    void union_set(const int x, const int y) {
        const auto x_parent = find(x);
        const auto y_parent = find(y);
        if (x_parent == y_parent)
            return;

        if (ranks_[x_parent] >= ranks_[y_parent]) {
            if (ranks_[x_parent] == ranks_[y_parent]) {
                ++ranks_[x_parent];
            }
            parents_[y_parent] = x_parent;            
        } else {
            parents_[x_parent] = y_parent;            
        }
    }

    int find(const int node) {
        if (parents_[node] == node) {
            return node;
        }
        parents_[node] = find(parents_[node]);
        return parents_[node];
    }
private:
    std::vector<int> ranks_;
    std::vector<int> parents_;
};

class Solution {
public:
    string smallestStringWithSwaps(string s, vector<vector<int>>& pairs) {
        UnionFind uf(s.size());
        for (const auto& pair : pairs) {
            uf.union_set(pair[0], pair[1]);
        }
        std::unordered_map<int, std::vector<int>> components;
        for (auto i = 0; i < s.size(); ++i) {
            components[uf.find(i)].emplace_back(i);
        }
        std::vector<char> ret(s.size());
        for (auto& [_, component] : components) {
            std::vector<char> partial_string(component.size());
            std::ranges::sort(component);
            std::ranges::transform(component, partial_string.begin(), [&s](const int i){return s[i];});
            std::ranges::sort(partial_string);
            for (auto i = 0; i < component.size(); ++i) {
                ret[component[i]] = partial_string[i];
            }
        }

        return std::string(ret.begin(), ret.end());
        
    }
};
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