leetcode 139. Word Break
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
class Solution {
HashMap<String,Boolean> map = new HashMap<>();
public boolean wordBreak(String s, List<String> wordDict) {
return help(s, wordDict);
}
public boolean help(String s, List<String> Dict){
if(map.containsKey(s)) return map.get(s);
if(Dict.contains(s)) {
map.put(s,true);
return true;
}
for(int i = 1; i< s.length() ; i++){
String left = s.substring(0,i);
String right = s.substring(i);
if(Dict.contains(right) && help(left,Dict)) {
map.put(s,true);
return true;
}
}
map.put(s,false);
return false;
}
}
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