IOM 2020, Блиц — Задача 23

The Blitz-contest of IOM-2020

Условие

You are given the sequence A=(1,5,10,3,15,x,y)A = (1, 5, 10, 3, 15, x, y). For how many positive integer pairs (x,y)(x, y) does the longest strictly increasing subsequence of AA have a length of 4?

Отговори

Решение

Внимание: Непълно решение

The source contains only the answer key, no worked solution.

Оригинал в Архива: iom-2020-blitz-tasks.pdf · официални решения: iom-2020-blitz-answers.pdf