<p>A <strong>transformation sequence</strong> from word <code>beginWord</code> to word <code>endWord</code> using a dictionary <code>wordList</code> is a sequence of words <code>beginWord -&gt; s<sub>1</sub> -&gt; s<sub>2</sub> -&gt; ... -&gt; s<sub>k</sub></code> such that:</p>

<ul>
	<li>Every adjacent pair of words differs by a single letter.</li>
	<li>Every <code>s<sub>i</sub></code> for <code>1 &lt;= i &lt;= k</code> is in <code>wordList</code>. Note that <code>beginWord</code> does not need to be in <code>wordList</code>.</li>
	<li><code>s<sub>k</sub> == endWord</code></li>
</ul>

<p>Given two words, <code>beginWord</code> and <code>endWord</code>, and a dictionary <code>wordList</code>, return <em>all the <strong>shortest transformation sequences</strong> from</em> <code>beginWord</code> <em>to</em> <code>endWord</code><em>, or an empty list if no such sequence exists. Each sequence should be returned as a list of the words </em><code>[beginWord, s<sub>1</sub>, s<sub>2</sub>, ..., s<sub>k</sub>]</code>.</p>

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

<pre>
<strong>Input:</strong> beginWord = &quot;hit&quot;, endWord = &quot;cog&quot;, wordList = [&quot;hot&quot;,&quot;dot&quot;,&quot;dog&quot;,&quot;lot&quot;,&quot;log&quot;,&quot;cog&quot;]
<strong>Output:</strong> [[&quot;hit&quot;,&quot;hot&quot;,&quot;dot&quot;,&quot;dog&quot;,&quot;cog&quot;],[&quot;hit&quot;,&quot;hot&quot;,&quot;lot&quot;,&quot;log&quot;,&quot;cog&quot;]]
<strong>Explanation:</strong>&nbsp;There are 2 shortest transformation sequences:
&quot;hit&quot; -&gt; &quot;hot&quot; -&gt; &quot;dot&quot; -&gt; &quot;dog&quot; -&gt; &quot;cog&quot;
&quot;hit&quot; -&gt; &quot;hot&quot; -&gt; &quot;lot&quot; -&gt; &quot;log&quot; -&gt; &quot;cog&quot;
</pre>

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

<pre>
<strong>Input:</strong> beginWord = &quot;hit&quot;, endWord = &quot;cog&quot;, wordList = [&quot;hot&quot;,&quot;dot&quot;,&quot;dog&quot;,&quot;lot&quot;,&quot;log&quot;]
<strong>Output:</strong> []
<strong>Explanation:</strong> The endWord &quot;cog&quot; is not in wordList, therefore there is no valid transformation sequence.
</pre>

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

<ul>
	<li><code>1 &lt;= beginWord.length &lt;= 5</code></li>
	<li><code>endWord.length == beginWord.length</code></li>
	<li><code>1 &lt;= wordList.length &lt;= 500</code></li>
	<li><code>wordList[i].length == beginWord.length</code></li>
	<li><code>beginWord</code>, <code>endWord</code>, and <code>wordList[i]</code> consist of lowercase English letters.</li>
	<li><code>beginWord != endWord</code></li>
	<li>All the words in <code>wordList</code> are <strong>unique</strong>.</li>
	<li>The <strong>sum</strong> of all shortest transformation sequences does not exceed <code>10<sup>5</sup></code>.</li>
</ul>

class Solution {
public:
    
    void dfs(vector<int> *par,int curr,int src,vector<int>& temp,vector<vector<string> >&res,vector<string>&wordList){
	
	
	if(curr==src){
		temp.push_back(curr);
		
		vector<string>ans;
		for(int i=temp.size()-1;i>=0;i--)
			ans.push_back(wordList[temp[i]]);			
		res.push_back(ans);
		
		temp.pop_back();	
		return;	
	}
	
	temp.push_back(curr);
	
	for(auto &x:par[curr]){
		dfs(par,x,src,temp,res,wordList);	
	}
	temp.pop_back();
	
}


void AllShortestPathsFromSourceToDestination(vector<int> *adj,int n,int src,int des,vector<vector<string> >&res,vector<string>&wordList){
	vector<int> dist(n,-1);
	queue<int>q;
	q.push(src);
	dist[src]=0;
	vector<int> par[n];

	while(!q.empty()){
		
		int node=q.front();
		q.pop();
		
		for(auto &x:adj[node]){
			if(dist[x]==-1){
				
				dist[x]=dist[node]+1;
				q.push(x);
				par[x].push_back(node);
			}
			
			else if(dist[x]==dist[node]+1){
				
				
				
				par[x].push_back(node);
			}
			
		}
		
	}

	
	vector<int>temp;
	dfs(par,des,src,temp,res,wordList);
	
	
	
	
}

vector<vector<string>> findLadders(string beginWord, string endWord, vector<string>& wordList) {
        
        vector<vector<string > >res;
		wordList.insert(wordList.begin(),beginWord);
        
		int n=wordList.size();
        for(int i=1;i<n;i++){
            if(wordList[i]!=endWord && i==n-1){
                return res;
            }
            else if(wordList[i]==endWord){
                swap(wordList[i],wordList[n-1]);
                break;
            }
        }
	    
        vector<int>adj[n];
		for(int i=0;i<n;i++){
            
            
            for(int j=i+1;j<n;j++){
                int count=max(wordList[j].size(),wordList[i].size())-min(wordList[j].size(),wordList[i].size());
                for(int k=0;k<min(wordList[j].size(),wordList[i].size());k++){
                    if(wordList[i][k]!=wordList[j][k]){
                        count++;
                        if(count>=2)
                                break;
                    }
                            
                }
                    
                if(count<=1){
                	
                    adj[i].push_back(j);
                    if(j!=n-1);
                    adj[j].push_back(i);
                }
                
            }
            
        }
       
	    AllShortestPathsFromSourceToDestination( adj, n,0,n-1,res,wordList);
    	return res;
    
}
};
11900