Create 212.Word-Search-II_v2.cpp

Trie/212.Word-Search-II/212.Word-Search-II_v2.cpp

@@ -0,0 +1,93 @@
+class Solution {
+    class TrieNode
+    {
+        public:
+        TrieNode* next[26];
+        bool isEnd;
+        int count = 0;
+        TrieNode()
+        {
+            for (int i=0; i<26; i++)
+                next[i]=NULL;
+            isEnd=false;
+            count=0;
+        }
+    };
+    TrieNode* root;
+    vector<string>rets;
+    int M, N;
+    bool visited[12][12];
+public:
+    vector<string> findWords(vector<vector<char>>& board, vector<string>& words) 
+    {
+        M=board.size();
+        N=board[0].size(); 
+        root=new TrieNode();        
+        for (int i=0; i<words.size(); i++)
+        {
+            TrieNode* node=root;
+            for (auto ch: words[i])
+            {            
+                if (node->next[ch-'a']==NULL)
+                    node->next[ch-'a']=new TrieNode();
+                node=node->next[ch-'a'];
+                node->count++;
+            }
+            node->isEnd=true;
+        }            
+
+        for (int i=0; i<M; i++)
+         for (int j=0; j<N; j++)
+         {   
+             TrieNode* node = root;          
+             string word;
+             visited[i][j]=1;
+             DFS(i,j,node,word,board);
+             visited[i][j]=0;
+         }
+
+        return rets;
+    }
+
+    void DFS(int i, int j, TrieNode* node, string& word, vector<vector<char>>& board)
+    {
+        if (node->next[board[i][j]-'a']==NULL) return;        
+        if (node->next[board[i][j]-'a']->count==0) return;
+
+        node = node->next[board[i][j]-'a'];
+        word.push_back(board[i][j]);
+
+        if (node->isEnd==true)
+        {
+            node->isEnd = false;
+            rets.push_back(word);
+            remove(root, word);
+        }
+
+        vector<pair<int,int>>dir={{1,0},{-1,0},{0,1},{0,-1}};        
+
+        for (int k=0; k<4; k++)
+        {
+            int x=i+dir[k].first;
+            int y=j+dir[k].second;
+            if (x<0||x>=M||y<0||y>=N) continue;
+            if (visited[x][y]==1) continue;
+
+            visited[x][y]=1;            
+            DFS(x,y,node,word,board);
+            visited[x][y]=0;                           
+        }        
+
+        word.pop_back();
+    }
+
+    void remove(TrieNode* root, string word)
+    {
+        TrieNode* node = root;
+        for (auto ch: word)
+        {
+            node = node->next[ch-'a'];
+            node->count --;
+        }
+    }
+};