What is the name of the algorithm described in each of the following definitions? And is it complexity

1) It is used for pattern matching, where a given pattern of size M and a string of size N. It skips unnecessary comparisons between the pattern and the string using a suffix-matrix and hence optimize the whole process.

2) It is used to search for a node in the graph by traversing from root node and explore the search as deep as possible until a dead end is found.

3) It is a greedy algorithm in graph theory that is used to find the tree with the lowest cost that connect all the nodes in a connected weighted graph.