questions are: 1. check if there is a winner in the Tic Tac Toe game. 2. 2D matrix and some restriction, find the min path. This is a DFS/BFS problem. 3. LCA with parent pointer. 4. largest continues sub array. 5. minimum window substring. 6. Find the smallest number of coins that add to a given amount. 7. Java Swing code about a board game, check errors in the code. The main error is: for each move you actually need to create a new matrix to represent the board.