<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:
    def smallestStringWithSwaps(self, s: str, pairs: List[List[int]]) -> str:
        '''
        https://leetcode.com/problems/smallest-string-with-swaps/solutions/2308250/python-dfs-graph-based-sol-explained-easy/?envType=company&envId=uber&favoriteSlug=uber-all&role=backend&difficulty=MEDIUM

        find connected components in the string and sort the components separately

We find the components using pairs

Say index = [1 ,3 , 5 , 7] are a component
so we sort the values ( s[1] , s[3] ,s[5] , s[7] ) and put them at 1,3,5,7 index respectively
        '''
        n = len(s)
        visited = [False]*n
        canGo = defaultdict(list)
        mainList = []
        #st = [] not needed
        
        for i,j in pairs:
            canGo[i].append(j)
            canGo[j].append(i)
        
        def dfs(node,path):
            visited[node] = True
            path.append(node)
            for adj in canGo[node]:
                if visited[adj] == False:
                    dfs(adj,path)
        
        for i in range(n):
            if visited[i] == True: continue
            path = []
            dfs(i,path)
            mainList.append(path)

        for lst in mainList:
            lst.sort()
            tmp = [s[i] for i in lst]
            tmp.sort()
            for i in range(len(lst)):
                s = s[:lst[i]]  + tmp[i] + s[lst[i]+1:]
            #for i, ch in zip(lst, tmp): this wont work e.g my output is "bdhhibtirxjoyywyy", but expected is "bdhhibtirjoxwyyyy" -> check x and w
            #    st.insert(i, ch)

        #return ''.join(st)
        return s
        
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