Thinking In C++. Volume 2: Practical Programming

         16.             Use UrandGen( ) to generate 100 numbers. (The size of the numbers does not matter.) Find which numbers in your range are congruent mod 23 (meaning they have the same remainder when divided by 23). Manually pick a random number yourself, and find if that number is in your range by dividing each number in the list by your number and checking if the result is 1 instead of just using find( ) with your value.

         17.             Fill a vector with numbers representing angles in radians. Using function object composition, take the sine of all the elements in your vector (see ).

         18.             Test the speed of your computer. Call srand(time(0)), then make an array of random numbers. Call srand(time(0)) again and generate the same number of random numbers in a second array. Use equal( ) to see if the arrays are the same. (If your computer is fast enough, time(0) will return the same value both times it is called.) If the arrays are not the same, sort them and use mismatch( ) to see where they differ. If they are the same, increase the length of your array and try again.

         19.             Create an STL-style algorithm transform_if( ) following the first form of transform( ) that performs transformations only on objects that satisfy a unary predicate. Objects that don’t satisfy the predicate are omitted from the result. It needs to return a new "end" iterator.

        20.             Create an STL-style algorithm that is an overloaded version of for_each( ) which follows the second form of transform( ) and takes two input ranges so it can pass the objects of the second input range a to a binary function that it applies to each object of the first range.

         21.             Create a Matrix class that is made from a vector >. Provide it with a friend ostream& operator<<(ostream&, const Matrix&) to display the matrix. Create the following binary operations using the STL function objects where possible: operator+(const Matrix&, const Matrix&) for matrix addition, operator*(const Matrix&, const vector&) for multiplying a matrix by a vector, and operator*(const Matrix&, const Matrix&) for matrix multiplication. (You might need to look up the mathematical meanings of the matrix operations if you don’t remember them.) Demonstrate each.

        22.             Using the characters "~`!@#$%^&*()_-+=}{[]|\:;"'<.>,?/", generate a codebook using an input file given on the command line as a dictionary of words. Don't worry about stripping off the non-alphabetic characters nor worry about case of the words in the dictionary file. Map each permutation of the character string to a word such as the following: "=')/%[}]|{*@?!"`,;>&^-~_:$+.#(<\"   apple "|]\~>#.+%(/-_[`':;=}{*"$^!&?),@<"   carrot "@=~['].\/<-`>#*)^%+,";&?!_{:|$}("   Carrot etc. Make sure that no duplicate codes or words exist in your code book. Use lexicographical_compare( ) to perform a sort on the codes. Use your code book to encode the dictionary file. Decode your encoding of the dictionary file, and make sure you get the same contents back.

        23.             Using the following names:

Jon Brittle

Jane Brittle

Mike Brittle

Sharon Brittle

George Jensen

Evelyn Jensen

Find all the possible ways to arrange them for a wedding picture.

        24.             After being separated for one picture, the bride and groom decided they wanted to be together for all of them. Find all the possible ways to arrange the people for the picture if the bride and groom (Jon Brittle and Jane Brittle) are to be next to each other.<#TIC2V2_CHAPTER8_I350>

        25.             A travel company wants to find out the average number of days people take to travel from one end of the continent to another. The problem is that in the survey, some people did not take a direct route and took much longer than is needed (such unusual data points are called "outliers"). Using the following generator following, generate travel days into a vector. Use remove_if( ) to remove all the outliers in your vector. Take the average of the data in the vector to find out how long people generally take to travel.

int travelTime() {

        // The "outlier"

        if(rand() % 10 == 0)

          return rand() % 100;

        // Regular route

        return rand() % 10 + 10;

}

 <#TIC2V2_CHAPTER8_I353>

        26.             Determine how much faster binary_search( ) is to find( ) when it comes to searching sorted ranges.<#TIC2V2_CHAPTER8_I354>