Time: 168 ms (74.30%), Space: 7.3 MB (36.77%) - LeetHub

Author: JanaSabuj

word-search/word-search.cpp

@@ -0,0 +1,54 @@
+class Solution {
+public:
+    int dx[4] = {0, 0, 1, -1};
+    int dy[4] = {1, -1, 0, 0};
+    
+    bool dfs(int i, int j, int idx, const string& word, vector<vector<char>>& board){                        
+        int n = board.size();
+        int m = board[0].size();
+        
+        int len = word.size();
+        if(idx == len - 1){
+            return board[i][j] == word[idx];
+        }
+        
+        if (board[i][j] != word[idx])
+            return false;
+        
+        
+        char old = board[i][j];
+        board[i][j] = '0';// visited
+        
+        for(int k = 0; k < 4; k++){
+            int r = i + dx[k];
+            int c = j + dy[k];
+            
+            if(r < 0 or r >= n or c < 0 or c >= m or board[r][c] == '0')
+                continue;
+                       
+            if (dfs(r, c, idx + 1, word, board))
+                return true;                        
+        }
+        
+        board[i][j] = old;// undo & backtrack
+        return false;
+    }
+    
+    bool exist(vector<vector<char>>& board, string word) {
+        int n = board.size();
+        int m = board[0].size();
+        int len = word.size();
+        
+        
+        for(int i = 0; i < n; i++){
+            for(int j = 0; j < m; j++){
+                if(board[i][j] == word[0]){                    
+                    if(dfs(i, j, 0, word, board))
+                        return true;
+                }
+            }
+        }
+        
+        return false;
+    }
+};