The annual snake festival is upon us and all the snakes of the kingdom have gathered to participate in the parade. The chef was tasked with reporting on the parade, so he decided to watch all the snakes first. When he sees the snake first, it will be his head, so he marks the "H". Snakes are long, and when they see the snake finally scurry away, they mark its tail with a "T". In the interim, when the snake is moving around it, or in the time between one snake and the next snake, it marks a '.'. Since the snakes come in a procession and one by one, a valid message would be something like "..H..T...HTH....T.", or "...", or "HT", while "T...H..H.T", "H..T..H", "H..H..T..T" would be invalid messages (see explanation below). Formally, a snake is represented by an 'H' followed by some (possibly null)'.' and then 'T'. A valid message is one that begins with the (probably zero-length) string '.' and then some (possibly zero) snakes, with some '.'s in between, and finally some (possibly zero) '.'s. The chef was devouring the festival food and was very sleepy. So his message may be invalid. You have to help him find out if his message is valid or not.

The annual snake festival is upon us and all the snakes of the kingdom have gathered to participate in the parade. The chef was tasked with reporting on the parade, so he decided to watch all the snakes first. When he sees the snake first, it will be his head, so he marks the "H". Snakes are long, and when they see the snake finally scurry away, they mark its tail with a "T". In the interim, when the snake is moving around it, or in the time between one snake and the next snake, it marks a '.'. Since the snakes come in a procession and one by one, a valid message would be something like "..H..T...HTH....T.", or "...", or "HT", while "T...H..H.T", "H..T..H", "H..H..T..T" would be invalid messages (see explanation below). Formally, a snake is represented by an 'H' followed by some (possibly null)'.' and then 'T'. A valid message is one that begins with the (probably zero-length) string '.' and then some (possibly zero) snakes, with some '.'s in between, and finally some (possibly zero) '.'s. The chef was devouring the festival food and was very sleepy. So his message may be invalid. You have to help him find out if his message is valid or not.

Database System Concepts

7th Edition

ISBN:9780078022159

Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Chapter1: Introduction

Section: Chapter Questions

Problem 1PE

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