Felomeng算法导论（第二版）学习笔记Chapter1

Algorithm: Informally, an algorithm is any well-defined computational procedure that takes some value, or set of values, as input and produces some value, or set of values, as output. An algorithm is thus a sequence of computational steps that transform the input into the output.
We can also view an algorithm as a tool for solving a well-specified computational problem. The statement of the problem specifies in general terms the desired input/output relationship. The algorithm describes a specific computational procedure for achieving that input/output relationship.
instance of a problem :In general, an instance of a problem consists of the input (satisfying whatever constraints are imposed in the problem statement) needed to compute a solution to the problem.
correct: An algorithm is said to be correct if, for every input instance, it halts with the correct output.
NPC: Nondeterministic Polynomial Complete