Recursive solving of the Problems using the "Divide & conquer" method

Abstract

The methodology for studying the theme "Recursive solving of the problem using the "divide & conquer" method" in preparing schoolchildren for Olympiads in informatics is illustrated in the article by solving the "Head on shoulders" problem. The solution of this problem includes several algorithms (subtasks) considered sequentially, namely: merge sort, counting the number of inversions in a permutation, the number of pairs of intersecting segments. The study of the method is based on the sequential solution of these subtasks. For each subtask, the following materials are given: the formulation of the subtask, the idea of a solution with a proposal to come up with an implementation on their own, the solution in the Pascal programming language. Distance learning system DL.GSU. BY is the effective technical base for teaching. The system allows to offer for a student a formulation of the task; to submit the solution for review; to get a verdict from the system — a correct or incorrect solution; for incorrect solution, the number of the test on which the solution did not pass is indicated. A student can take a test (input and output data), on which his solution did not pass, fgure out what the error is in his program, correct and send the solution again.