<p>Given an array of strings <code>words</code> representing an English Dictionary, return <em>the longest word in</em> <code>words</code> <em>that can be built one character at a time by other words in</em> <code>words</code>.</p>

<p>If there is more than one possible answer, return the longest word with the smallest lexicographical order. If there is no answer, return the empty string.</p>

<p>Note that the word should be built from left to right with each additional character being added to the end of a previous word.&nbsp;</p>

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

<pre>
<strong>Input:</strong> words = [&quot;w&quot;,&quot;wo&quot;,&quot;wor&quot;,&quot;worl&quot;,&quot;world&quot;]
<strong>Output:</strong> &quot;world&quot;
<strong>Explanation:</strong> The word &quot;world&quot; can be built one character at a time by &quot;w&quot;, &quot;wo&quot;, &quot;wor&quot;, and &quot;worl&quot;.
</pre>

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

<pre>
<strong>Input:</strong> words = [&quot;a&quot;,&quot;banana&quot;,&quot;app&quot;,&quot;appl&quot;,&quot;ap&quot;,&quot;apply&quot;,&quot;apple&quot;]
<strong>Output:</strong> &quot;apple&quot;
<strong>Explanation:</strong> Both &quot;apply&quot; and &quot;apple&quot; can be built from other words in the dictionary. However, &quot;apple&quot; is lexicographically smaller than &quot;apply&quot;.
</pre>

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

<ul>
	<li><code>1 &lt;= words.length &lt;= 1000</code></li>
	<li><code>1 &lt;= words[i].length &lt;= 30</code></li>
	<li><code>words[i]</code> consists of lowercase English letters.</li>
</ul>

class Solution {
public:
    vector<vector<int>> adj;
    int n;
    int ans;
    int ansi;
    vector<string> a;
    
    void pj(vector<vector<int>> a) {
        for(int i = 0 ; i < a.size() ; i++){
            printf("%d : ",i);
            for(auto j : a[i]){
                printf("%d ",j);
            }
            printf("\n");
        }
    }
    
    void getL(int x) {
        vector<int> at;
        at.push_back(x);
        int sz = 1;
        while(at.size() > 0) {
            vector<int> nat;
            sz++;
            if(sz > ans) {
                ans = sz;
                ansi = at[0];
            }
            
            
            
            for(auto i : at) {
                if(sz == ans) {
                    if(a[ansi] > a[i]) {
                        ansi = i;
                    }
                }
                for(auto j : adj[i]) {
                    nat.push_back(j);
                }
            }
            at = nat;
            
        }
    }
        
    
    string longestWord(vector<string>& aa) {
        a = aa;
        n = a.size();
        adj.resize(n);
        ans = 0;
        ansi = -1;
        
        for(int i = 0 ; i < n ; i++) {
            for(int j = i + 1 ; j < n ; j++) {
                if(a[i].size() == a[j].size() + 1) {
                    if(a[i].substr(0,a[j].size()) == a[j]) {
                        adj[j].push_back(i);
                    }
                }
                
                if(a[j].size() == a[i].size() + 1) {
                    if(a[j].substr(0,a[i].size()) == a[i]) {
                        adj[i].push_back(j);
                    }
                }
            }
        }
        
        for(int i = 0 ; i < n ; i++) {
            if(a[i].size() != 1) {
                continue;
            }
            getL(i);
        }
        if(ansi == -1) {
            return "";
        }
        
        
        
        return a[ansi];
    }
};
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