<p>Given a string <code>s</code> and a dictionary of strings <code>wordDict</code>, return <code>true</code> if <code>s</code> can be segmented into a space-separated sequence of one or more dictionary words.</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;leetcode&quot;, wordDict = [&quot;leet&quot;,&quot;code&quot;]
<strong>Output:</strong> true
<strong>Explanation:</strong> Return true because &quot;leetcode&quot; can be segmented as &quot;leet code&quot;.
</pre>

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

<pre>
<strong>Input:</strong> s = &quot;applepenapple&quot;, wordDict = [&quot;apple&quot;,&quot;pen&quot;]
<strong>Output:</strong> true
<strong>Explanation:</strong> Return true because &quot;applepenapple&quot; can be segmented as &quot;apple pen apple&quot;.
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> false
</pre>

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

<ul>
	<li><code>1 &lt;= s.length &lt;= 300</code></li>
	<li><code>1 &lt;= wordDict.length &lt;= 1000</code></li>
	<li><code>1 &lt;= wordDict[i].length &lt;= 20</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>
</ul>

class Trie {
    public:
        Trie *children[26]={NULL};
        bool isWord=false;
        void addWord(string word){
            Trie *curr = this;
            for(auto ch:word){
                if(curr->children[ch-'a']==NULL)curr->children[ch-'a']=new Trie();
                curr= curr->children[ch-'a'];
            }
            curr->isWord=true;
        }
        bool searchWord(string word){
            Trie *curr = this;
            for(auto ch:word){
                if(curr->children[ch-'a']==NULL)return false;
                curr=curr->children[ch-'a'];
            }
            return curr->isWord;
        }
};
class Solution {
public:
    bool dfs(string& s,int index,Trie *root, vector<int>& dp) {
        if(index>=s.length())return true;
        if(dp[index]!=-1)return dp[index];
        string current= "";
        for(int i=index;i<s.length();i++){
            current+=s[i];
            if(root->searchWord(current)){
                if(dfs(s,i+1,root,dp)){
                    return dp[index]=true;
                }
            }
        }
        return dp[index]=false;
       
    }
    bool wordBreak(string s, vector<string>& wordDict) {
        Trie *root = new Trie();
        vector<int>dp(s.length(),-1);
        for(auto word:wordDict) root->addWord(word);
        return dfs(s,0,root,dp);
    }
};
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