# Lab Assignment 1

Goals:
1. Understanding of binary search.
2. Understanding of maps/permutations, indirection, and swapping.
Requirements:
1. Write a C program to maintain n counters indexed by 0 .. n-1. n will be the first input value and all counters are initially
valued as zero. The following operations will then appear, one per line, in the input:
a. 0 - terminate execution.
b. 1 - print the counters in ascending index value order as (index, count) pairs. (O(n) time)
c. 2 - print the counters in ascending counter value order as (index, count) pairs. (O(n) time)
d. 3 i - add one to the counter indexed by i. (O(log n) time)
e. 4 i - subtract one from the counter indexed by i. (O(log n) time)
f. 5 i j - determine the number of counters whose values are no smaller than i and no larger than j. (O(log n) time)
The input will be read from standard input (stdin) as either keyboard typing or as a shell redirect (<) from a file.
2. Submit your program on Blackboard by 10:45 am on September 25. One of the comment lines should indicate the
compilation command used on OMEGA.
Getting Started:
1. Review binary search and obtain a copy of binarySearchRange.c from the course web page. Code similar to this
will be useful in implementing operations 3, 4, and 5.
2. Your program should dynamically allocate three tables - map, index, and count. (If you wish, the last two tables may
be implemented as an array of structs.) index[i] indicates which of the n counters has its value presently stored as
count[i]. map[i] is used to find the counter with index i, i.e. it is always true that index[map[i]]==i.
Operation 2 may be coded as:
for (i=0;i<n;i++)
printf("%d %d\n",index[i],count[i]);
Operation 1 may be coded as:
for (i=0;i<n;i++)
printf("%d %d\n",i,count[map[i]]);
3. You should implement and completely debug operation 3 before implementing operation 4.
4. Your code must satisfy the indicated time bounds by using binary search when possible.