word break problem

Author: Alagappan Maruthappan

word_break.py

@@ -0,0 +1,42 @@
+# https://leetcode.com/problems/word-break/description/
+
+
+class Solution:
+    def __init__(self):
+        self.soln = []
+
+    def wordBreakUtil(self, s, wordDict, cache, start_index, soln):
+        """
+        :type s: str
+        :type wordDict: List[str]
+        :rtype: bool
+        """
+        if start_index >= len(s):
+            self.soln.append(soln)
+        if not cache[start_index] is None:
+            return cache[start_index]
+        ans = False
+        for index in range(start_index+1, len(s) + 1):
+            word = s[start_index:index]
+            if word in wordDict:
+                soln.append(word)
+                self.wordBreakUtil(s, wordDict, cache, index, soln)
+                soln.pop()
+        cache[start_index] = ans
+
+    def wordBreak(self, s, wordDict):
+        cache = [None] * len(s)
+        return self.wordBreakUtil(s, wordDict, cache, 0, [])
+
+
+s = "leetcode"
+wordDict = ["leet", "code"]
+assert Solution().wordBreak(s, wordDict)
+
+s = "catsandog"
+wordDict = ["cats", "dog", "sand", "and", "cat"]
+assert not Solution().wordBreak(s, wordDict)
+
+s = "applepenapple"
+wordDict = ["apple", "pen"]
+assert Solution().wordBreak(s, wordDict)