CS1101X: Programming Methodology

Recitation 6 Arrays I

CS1101X Recitation #6 2

Task 1: Learning-by-mistake

To be given out at the recitation.

CS1101X Recitation #6 3

Task 2: isSorted

A program IsSortedArray.java to test whether a list of integers in sorted in non-decreasing order. The method isSorted() returns true if the array is sorted; it returns false otherwise.

Based on what we have discussed for task 1, can you write the isSorted() method?

3 5 5 7 18 21 true

1 3 4 7 6 9 11 false

CS1101X Recitation #6 4

Task 3: Second largest

Given a list of integers, determine the second largest value in the list. (Assuming that the list contains at least 2 values.)

10 3 7 15 11 21 15

5 8 7 9 2 8 1 3 8

12 7 9 12 10 3 12

CS1101X Recitation #6 5

Task 4: Pascal’s Triangle (1/3)

Blaise Pascal was a scientist, mathematician par excellence who lived in the 17th century. Some of his mathematical work was fundamental to the theory of probability. There is also a programming language named after him (though in no real sense related to him). More of him in this website (for those who are interested): http://www-gap.dcs.st-and.ac.uk/~history/Mathematicians/Pascal.html

CS1101X Recitation #6 6

Task 4: Pascal’s Triangle (2/3)

In this problem, you are asked to generate Pascal's Triangle. Pascal's Triangle is useful in many areas from probability to polynomials to setting programming questions. It is a triangle of integers with 1 on top and down the sides. Any number in the interior equals the sum of the two numbers above it. For example, here are the first 5 rows of the triangle. 1

1 11 2 1

1 3 3 1

1 4 6 4 1

CS1101X Recitation #6 7

Task 4: Pascal’s Triangle (3/3)

Write a program to generate a Pascal’s Triangle as shown. It should be observed that the next row of the Pascal’s triangle can be generated from the previous row. Thus, using an array to store the values of the previous rows seems appropriate.

11 11 2 11 3 3 11 4 6 4 11 5 10 10 5 1

Output for n (number of rows) = 6.

CS1101X Recitation #6 8

To be continued…

More problems on arrays (including array of objects) at the next recitation.

CS1101X Recitation #6 9

End of Recitation #6