Given a non-empty string s and a dictionary wordDict containing a list of non-empty words, determine if s can be segmented into a space-separated sequence of one or more dictionary words.

Note:

  • The same word in the dictionary may be reused multiple times in the segmentation.
  • You may assume the dictionary does not contain duplicate words.

Example 1:

Input: s = "leetcode", wordDict = ["leet", "code"]
Output: true
Explanation: Return true because "leetcode" can be segmented as "leet code".

Example 2:

Input: s = "applepenapple", wordDict = ["apple", "pen"]
Output: true
Explanation: Return true because "applepenapple" can be segmented as "apple pen apple".
             Note that you are allowed to reuse a dictionary word.

Example 3:

Input: s = "catsandog", wordDict = ["cats", "dog", "sand", "and", "cat"]
Output: false

Solution : Dynamic Programming

Bottom Up Approach

class Solution {
    public boolean wordBreak(String s, List<String> wordDict) {
        
        HashSet<String> set = new HashSet<>(wordDict);
        
        boolean[] dp = new boolean[s.length()+1];
        
        dp[0] = true;
        
        for(int i=1;i<=s.length();i++)
        {
            for(int j=i-1;j>=0;j--)
            {
                String substring = s.substring(j,i);
                
                if(set.contains(substring))
                {
                    if(dp[j] == true)
                    {
                        dp[i] = true;
                    }
                }
                
            }
        }
        return dp[s.length()];
        
    }
}

Time Complexity: O(M * N)

Space Complexity: O(N)

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