Programming Exercises

Debugging Problem

The code in pearson_problem.cpp compiles successfully with

g++ -o pearson pearson_problem.cpp

However, the unit tests fail during runtime:

./pearson

Assertion failed: (std::abs(numeric::correlation(x, n, z, n)) - (-1.0)
< tolerance), function main, file pearson_problem.cpp, line 106.

Find and correct 7 logical errors in pearson_problem.cpp.

Code Comprehension

Review the code in numeric.hpp and answer the following questions.

1. What is the worse-case time and space complexities of the following function?

   template <typename T> inline double mad(T* xs, size_t n)

2. What is the average-case time complexity of the following function?

   template <typename T> inline double median(T* xs, size_t n)

Problem Solving

Write a program that finds the fourth most frequent value in an integer array. In the case of ties in frequency among multiple values, return the smallest of such values.

For example, given the values (as command-line argument inputs)

4 4 1 2 2 2 2 3 3 3 5 5 5 6 1 5 9

the program should print

1