<p>Given a string <code>s</code> and a dictionary of strings <code>wordDict</code>, add spaces in <code>s</code> to construct a sentence where each word is a valid dictionary word. Return all such possible sentences in <strong>any order</strong>.</p>

<p><strong>Note</strong> that the same word in the dictionary may be reused multiple times in the segmentation.</p>

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

<pre>
<strong>Input:</strong> s = &quot;catsanddog&quot;, wordDict = [&quot;cat&quot;,&quot;cats&quot;,&quot;and&quot;,&quot;sand&quot;,&quot;dog&quot;]
<strong>Output:</strong> [&quot;cats and dog&quot;,&quot;cat sand dog&quot;]
</pre>

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

<pre>
<strong>Input:</strong> s = &quot;pineapplepenapple&quot;, wordDict = [&quot;apple&quot;,&quot;pen&quot;,&quot;applepen&quot;,&quot;pine&quot;,&quot;pineapple&quot;]
<strong>Output:</strong> [&quot;pine apple pen apple&quot;,&quot;pineapple pen apple&quot;,&quot;pine applepen apple&quot;]
<strong>Explanation:</strong> Note that you are allowed to reuse a dictionary word.
</pre>

<p><strong class="example">Example 3:</strong></p>

<pre>
<strong>Input:</strong> s = &quot;catsandog&quot;, wordDict = [&quot;cats&quot;,&quot;dog&quot;,&quot;sand&quot;,&quot;and&quot;,&quot;cat&quot;]
<strong>Output:</strong> []
</pre>

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

<ul>
	<li><code>1 &lt;= s.length &lt;= 20</code></li>
	<li><code>1 &lt;= wordDict.length &lt;= 1000</code></li>
	<li><code>1 &lt;= wordDict[i].length &lt;= 10</code></li>
	<li><code>s</code> and <code>wordDict[i]</code> consist of only lowercase English letters.</li>
	<li>All the strings of <code>wordDict</code> are <strong>unique</strong>.</li>
	<li>Input is generated in a way that the length of the answer doesn&#39;t exceed&nbsp;10<sup>5</sup>.</li>
</ul>

class Solution {
public:
    bool findWords(string& s, unordered_map<string,bool>& dict,int start, int curr,vector<vector<int>>& dp,string currResult, vector<string>& result){

        string currWord = s.substr(start,curr-start+1);
        if(curr==s.length()-1){
            if(dict.find(currWord)!=dict.end()){
                if(currResult.length()>0){
                    currResult+=' ';
                }
                result.push_back(currResult+currWord);
               // cout<<currWord<<" ";
            }
         //   cout<<currWord<<" ";
            return 0;
        }
        if(dp[start][curr]!=-1){
            //return dp[start][curr];
        }
        if(dict.find(currWord)==dict.end()){
            
            dp[start][curr] = findWords(s,dict,start,curr+1,dp,currResult,result);
            return dp[start][curr];
        }
      //  cout<<currWord<<" ";
        
        
        dp[start][curr] = findWords(s,dict,start,curr+1,dp,currResult,result);
        if(currResult.length()>0){
            currResult+=' ';
        }
        currResult.append(currWord);
        dp[start][curr] = findWords(s,dict,curr+1,curr+1,dp,currResult,result);
        return dp[start][curr];

    }

    vector<string> wordBreak(string s, vector<string>& wordDict) {
         unordered_map<string,bool> dict;
         vector<string> result;
        vector<vector<int>> dp(s.length(),vector<int>(s.length(),-1));
        for(int i=0;i<wordDict.size();i++){
            dict[wordDict[i]] = 1;
        }
        findWords(s,dict,0,0,dp,"",result);
        return result;
  
    }
};


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