Programming

1. Programming Summary

2. Exercise – Remove Duplicates • Download remove_duplicates_ex.c and implement the functionvoid remove_duplicates(Node *head); • remove_duplicates() accepts a list sorted in ascending order and deletes duplicate nodes from the list, leaving a single node for every value. • Ideally, the list should only be traversed once.

3. Clues in the Question • remove_duplicates does not return a value – what does it mean? • Why do we care that the list is sorted? Does the sorting order makes a difference?

4. Solution void remove_duplicates(Node* head) { Node *current = head, *tmp = NULL; /* do nothing if the list is empty */ if (current == NULL) return; /* Compare current node with next node */ while (current->next != NULL) { if (current->data == current->next->data) { tmp = current->next; current->next = current->next->next; free(tmp); } else { /* only advance if no deletion */ current = current->next; } } }

5. Sample Theoretical Question • What’s printed on the screen when the following program is run? • change_val.c • And what do these function do? What’s missing and how will you fix it? • secret1.c • secret2.c

6. Parentheses Checking • Implement a function such that – • Input: string s that contains (among other things) parentheses • Output: 0 if the parentheses’ nesting is illegal, non-zero otherwise • For example – (()())() is legal, while ())() and (()(()) are not. • Write a program that accepts a string from the user and checks the parentheses.

7. Palindrome • A palindrome is string that reads the same backward or forward. • For example: amanaplanacanalpanama (A man, a plan, a canal, Panama!( • Write a recursive function that checks if a string is a palindrome. • Write a program that reads a string from the user and checks if it’s a palindrome.

8. Max Distance • Write a structure of a point in 2D space and a distance function between two points • Write a program that gets a series of points from the user and outputs the largest distance between a pair of points • The number of points is given by the user before the points are read in • The distance between points [x1, y1] and [x2, y2] is • Solution – max_distance.c

9. Max Distance • Write a structure of a point in 2D space and a distance function between two points • Write a program that gets a series of points from the user and outputs the largest distance between a pair of points and the points themselves • The number of points is given by the user before the points are read in • Solution – max_distance2.c, max_distance3.c

10. Is In Circle? • Define two structures – a point and a circle • Implement a function is_in_circle that accepts a point and a circle, and returns 1 if the point is in the circle, 0 otherwise • Write a program that accepts n circles from the user and one point, and outputs the number of circles containing that point • n is user input!

11. Split List • Implement a linked list where each item simply contains an integer • Input a number n from the user, and split the original list into two lists such that the first contains all the elements smaller than n, and the other contains all the others • Display both linked lists on the screen

12. Functions To Remember • stdio.h • printf, scanf, putchar, getchar • string.h • strlen, strcpy, strcat, strcmp, strchr, strstr • ctype.h • tolower, toupper, islower, isupper, … • stdlib.h • atof, atoi, malloc, free, exit

13. Solving A Problem • Read the entire question, beginning to end, then read it again. • Make sure you understand the requirements. • Break down the problem into logical steps • how do I get the input? • what kind of processing is needed? • what about the output? • Write your solution in a clear and concise manner (make sure you cover all your bases) • “compile and run”

14. The No. 1 Rule • Your grader is human, treat him as such!