Create replace-words.cpp

Author: kamyu104

C++/replace-words.cpp

@@ -0,0 +1,50 @@
+// Time:  O(n)
+// Space: O(t), t is the number of nodes in trie
+
+class Solution {
+public:
+    string replaceWords(vector<string>& dict, string sentence) {
+        TrieNode trie;
+        string result;
+        for (const auto& s : dict) {
+            trie.Insert(s);
+        }
+        auto curr = &trie;
+        for (int i = 0; i < sentence.length(); ++i) {
+            if (sentence[i] == ' ' || !curr || !curr->isString) {
+                result += sentence[i];
+            }
+            if (sentence[i] == ' ') {
+                curr = &trie;
+            } else if (curr && !curr->isString) {
+                curr = curr->leaves[sentence[i]];
+            }
+        }
+        return result;
+    }
+
+private:
+    struct TrieNode {
+        bool isString = false;
+        unordered_map<char, TrieNode *> leaves;
+        
+        void Insert(const string& s) {
+            auto* p = this;
+            for (const auto& c : s) {
+                if (p->leaves.find(c) == p->leaves.cend()) {
+                    p->leaves[c] = new TrieNode;
+                }
+                p = p->leaves[c];
+            }
+            p->isString = true;
+        }
+        
+        ~TrieNode() {
+            for (auto& kv : leaves) {
+                if (kv.second) {
+                    delete kv.second;
+                }
+            }
+        }
+    };
+};