Update 140_Word_Break_II.java

Author: Sean Prashad

Backtracking/140_Word_Break_II.java

@@ -0,0 +1,34 @@
+class Solution {
+    public List<String> wordBreak(String s, List<String> wordDict) {
+        Set<String> dict = new HashSet<>(wordDict);
+        Map<String, List<String>> memo = new HashMap<>();
+
+        return helper(s, dict, memo);
+    }
+
+    private List<String> helper(String s, Set<String> dict, Map<String, List<String>> memo) {
+        if (memo.containsKey(s)) {
+            return memo.get(s);
+        }
+
+        List<String> result = new ArrayList<>();
+        if (dict.contains(s)) {
+            result.add(s);
+        }
+
+        for (int i = 1; i < s.length(); i++) {
+            String word = s.substring(0, i);
+
+            if (dict.contains(word)) {
+                List<String> tmp = helper(s.substring(i), dict, memo);
+
+                for (String remainder : tmp) {
+                    result.add(word + " " + remainder);
+                }
+            }
+        }
+
+        memo.put(s, result);
+        return result;
+    }
+}