Create 588.Design-In-Memory-File-System.cpp

Trie/588.Design-In-Memory-File-System/588.Design-In-Memory-File-System.cpp

@@ -0,0 +1,86 @@
+class FileSystem {
+    class TrieNode
+    {
+        public:
+        map<string,TrieNode*>Map;
+        bool isFile;
+    };
+    TrieNode* root;
+    unordered_map<string,string>FileContents;
+
+public:
+    FileSystem() 
+    {
+        root=new TrieNode();
+    }
+
+    vector<string> ls(string path) 
+    {
+        TrieNode* node=root;
+        string str;
+        for (int i=1; i<path.size(); i++)
+        {
+            int i0=i;
+            while (i<path.size() && path[i]!='/')
+                i++;
+            str=path.substr(i0,i-i0);
+            node=node->Map[str];
+        }
+
+        if (node->isFile)
+            return {str};
+        else
+        {
+            vector<string>results;
+            for (auto a:node->Map)
+                results.push_back(a.first);
+            return results;
+        }
+    }
+
+    void mkdir(string path) 
+    {
+        TrieNode* node=root;
+        for (int i=1; i<path.size(); i++)
+        {
+            int i0=i;
+            while (i<path.size() && path[i]!='/')
+                i++;
+            string str=path.substr(i0,i-i0);
+            if (node->Map.find(str)==node->Map.end())
+                node->Map[str]=new TrieNode();                        
+            node=node->Map[str];
+        }
+    }
+
+    void addContentToFile(string filePath, string content) 
+    {
+        TrieNode* node=root;
+        for (int i=1; i<filePath.size(); i++)
+        {
+            int i0=i;
+            while (i<filePath.size() && filePath[i]!='/')
+                i++;
+            string str=filePath.substr(i0,i-i0);
+            if (node->Map.find(str)==node->Map.end())
+                node->Map[str]=new TrieNode();                        
+            node=node->Map[str];
+        }
+        node->isFile=1;
+        FileContents[filePath]+=content;
+    }
+
+    string readContentFromFile(string filePath) 
+    {
+        return FileContents[filePath];
+    }
+};
+
+/**
+ * Your FileSystem object will be instantiated and called as such:
+ * FileSystem obj = new FileSystem();
+ * vector<string> param_1 = obj.ls(path);
+ * obj.mkdir(path);
+ * obj.addContentToFile(filePath,content);
+ * string param_4 = obj.readContentFromFile(filePath);
+ */