Problem 1You are to write two functions, printString() and testString(), which are called from the main function.printString () should print characters from the given string to std::cout with a space after every character and a newline at the end.testString () should return true if the string has only repeated pairs of characters (e.g., “hheelllloo”, “ookk”, “aabbcc”), and false otherwise. See the main() to see how the two functions are called.Some sample runs are given below:string: “hheelllloo”printString prints: h e l l o h e l l otestString returns: truestring: “ookk”printString prints: o k o ktestString returns: truestring: “aabbcc”printString prints: a b a ctestString returns: falseNote:Write only the two functions in the space provided.You can change the main function for your own testing. Your code will be tested with a similar main function.Hints:You can access the i-th character of a string s with s[i].The number of characters in the string is s.size().File submission: Upload prob1.cpp with the two functions. Do not change the name of the given file (it should remain prob1.cpp)COMMAND TO COMPILE AND RUN CODE ON LINUX/TUFFIX:clang++ -std=c++17 prob1.cpp./a.out--------------------------------------------------------------------------------------------------------------------------------------------------------------------Problem 2You are given the partial implementation of class IntegerLinkedList which stores integers in a singly linked list. Add a public member function that does the following: bool checkList(): returns true if the linked list contains only repeated pairs of integers (as in Problem 1, e.g., 10,10, 20, 20, 30, 30); false otherwise. You may assume that the list is not empty.For example, checkList() should return true for the the linked list shown below. A main function (prob2.cpp) is given to you to add data values to the linked list and test your function. Other examples are given in the main function.Note:You must implement all your code in the given cpp file called IntegerLinkedList.cppYou cannot add other member variables and functions to class IntegerLinkedList.You can change the main function for your own testing. Your code will be tested with a similar main function. File submission: Upload exactly one file:IntegerLinkedList.cpp Command to compile and run on Linux/Tuffix:clang++ -std=c++17 prob2.cpp IntegerLinkedList.cpp./a.ou -----------------------------------------------------------------------------------------------------------------------------------------------------------------Problem 3Add a recursive Boolean function called checkRecurse to class IntegerLinkedList to check if the linked list contains only repeated pairs of integers (as in Problem 2). You may assume that the list is not empty. A recursion “helper” function is already included in class IntegerLinkedList. You only need to write the recursive function.For example, checkRecurseHelper should return true for the linked list shown below. A main function (prob3.cpp) is given to you to add data values to the linked list and test your function. Other examples are given in the main function.Note:A non-recursive version of the function will get no credit. The function should not have any loops at all. Do not use any global variables. Do not add member variables to the class. Do not change the contents of the linked list.Write the recursive function in IntegerLinkedList.cpp.You can change the main function for your own testing. Your code will be tested with a similar main function. File submission: Upload exactly one file:IntegerLinkedList.cpp Command to compile and run on Linux/Tuffix (RECOMMENDED):clang++ -std=c++17 prob2.cpp IntegerLinkedList.cpp./a.out