store C programming projects:
arb_int: a C_string API allows any type of integer to do +/-/* calculations
mnist: load binary image data from MNIST database and store image data in a linked-list
trie: build a trie struct API that allows insert, remove, traverse, destory and get value
connect4: A game similar to connect4 with choices of human and AI players. The board height, width and runs to win are decided by user.