<p>You are given an array <code>arr</code> of size <code>n</code> consisting of <strong>non-empty</strong> strings.</p>

<p>Find a string array <code>answer</code> of size <code>n</code> such that:</p>

<ul>
	<li><code>answer[i]</code> is the <strong>shortest</strong> <span data-keyword="substring">substring</span> of <code>arr[i]</code> that does <strong>not</strong> occur as a substring in any other string in <code>arr</code>. If multiple such substrings exist, <code>answer[i]</code> should be the <span data-keyword="lexicographically-smaller-string">lexicographically smallest</span>. And if no such substring exists, <code>answer[i]</code> should be an empty string.</li>
</ul>

<p>Return <em>the array </em><code>answer</code>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> arr = [&quot;cab&quot;,&quot;ad&quot;,&quot;bad&quot;,&quot;c&quot;]
<strong>Output:</strong> [&quot;ab&quot;,&quot;&quot;,&quot;ba&quot;,&quot;&quot;]
<strong>Explanation:</strong> We have the following:
- For the string &quot;cab&quot;, the shortest substring that does not occur in any other string is either &quot;ca&quot; or &quot;ab&quot;, we choose the lexicographically smaller substring, which is &quot;ab&quot;.
- For the string &quot;ad&quot;, there is no substring that does not occur in any other string.
- For the string &quot;bad&quot;, the shortest substring that does not occur in any other string is &quot;ba&quot;.
- For the string &quot;c&quot;, there is no substring that does not occur in any other string.
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> arr = [&quot;abc&quot;,&quot;bcd&quot;,&quot;abcd&quot;]
<strong>Output:</strong> [&quot;&quot;,&quot;&quot;,&quot;abcd&quot;]
<strong>Explanation:</strong> We have the following:
- For the string &quot;abc&quot;, there is no substring that does not occur in any other string.
- For the string &quot;bcd&quot;, there is no substring that does not occur in any other string.
- For the string &quot;abcd&quot;, the shortest substring that does not occur in any other string is &quot;abcd&quot;.
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>n == arr.length</code></li>
	<li><code>2 &lt;= n &lt;= 100</code></li>
	<li><code>1 &lt;= arr[i].length &lt;= 20</code></li>
	<li><code>arr[i]</code> consists only of lowercase English letters.</li>
</ul>

class Solution:
    def generateSubstrings(self, currWordSubstrings, word):
        for i in range(len(word)):
            for j in range(i, len(word)):
                currWordSubstrings.add(word[i:j+1])

    def findUncommonSubstrings(self, substringsPerWord, shortestUncommonSubstrings, currIdx):
        currWordSubstrings = substringsPerWord[currIdx]
        for substring in currWordSubstrings:
            isValidCandidate = True
            for i in range(len(substringsPerWord)):
                if i == currIdx:
                    continue
                if substring in substringsPerWord[i]:
                    isValidCandidate = False
                    break
            if isValidCandidate:
                shortestUncommonSubstrings[currIdx].append(substring)

    def findShortestSubstring(self, substrings):
        minLength = float("inf")
        shortestSubstring = substrings[0] if substrings else ""

        for substring in substrings:
            if len(substring) < minLength:
                minLength = len(substring)
                shortestSubstring = substring
            elif len(substring) == minLength and substring < shortestSubstring:
                shortestSubstring = substring

        return shortestSubstring
        
    def shortestSubstrings(self, arr: List[str]) -> List[str]:
        substringsPerWord = [set() for _ in range(len(arr))]
        shortestUncommonSubstrings = [[] for _ in range(len(arr))]

        for i in range(len(arr)):
            self.generateSubstrings(substringsPerWord[i], arr[i])

        for i in range(len(arr)):
            self.findUncommonSubstrings(substringsPerWord, shortestUncommonSubstrings, i)

        for i in range(len(arr)):
            shortestUncommonSubstrings[i] = self.findShortestSubstring(shortestUncommonSubstrings[i])

        return shortestUncommonSubstrings
        

        
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