Create 140. Word Break II (#488)

Author: Chayandas07

140. Word Break II

@@ -0,0 +1,20 @@
+class Solution {
+private:
+    void backtrack(string& s, int index, unordered_set<string>& set, string curr, vector<string>& res){
+        if (index == s.length()) {res.push_back(curr); return;}
+        string t = "";
+        for (int i = index; i < s.size(); i++){
+            t += s[i];
+            if (set.find(t) != set.end()){
+                backtrack(s, i+1, set, curr + t + (i < s.length()-1 ? " ":""), res);
+            }
+        }
+    }
+public:
+    vector<string> wordBreak(string s, vector<string>& wordDict) {
+        vector<string> res;
+        unordered_set<string> set(wordDict.begin(), wordDict.end());
+        backtrack(s, 0, set, "", res);
+        return res;
+    }
+};