adding lab 5

labs/05_vectors/README.md

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+# Lab 5 — Vec Implementation
+
+## Checkpoint 1
+*estimate: 20 minutes*
+
+- Team up with one student in your lab section. MEET SOMEONE NEW! You may not work
+with someone who was on your team for Lab 4. Ask a TA or mentor to help you find a partner.
+If the number of students in the room is not even, the graduate TA will approve a single team with 3
+members.
+- Introduce yourself to your teammate. Ask them to share something about themselves (e.g. hobbies,
+sports, favorite music, etc.) Learn something new about your teammate (even if you already know
+them).
+
+For each function below, assign different letters to each of the data sizes that at first glance might have impact
+on the running time of the function. Be sure to consider integer value, size of vector, and length of string.
+Then give the big O notation of the function in terms of those variables.
+
+```cpp
+int foobar (const std::vector<std::string> &a, int b) {
+    int answer = 0;
+    for (int i = 0; i < a.size(); i+=b) {
+        answer++;
+    }
+    return answer;
+}
+```
+
+```cpp
+void foo2 (const std::vector<int> &a, std::string &b) {
+    b.clear();
+    for (int i = 0; i < a.size(); i++)
+    {
+        if (a[i] > 0)
+            b.push_back('+');
+        else
+            b.push_back('-');
+    }
+}
+```
+
+```cpp
+std::vector<int> foo3 (const std::vector<int> &a, const std::string &b) {
+    return std::vector<int>(b.size(),a.size());
+}
+```
+
+```cpp
+int foo3 (const std::vector<std::string> &a, const std::string& b) {
+    int ret = 0;
+    for (int i=0; i<a.size(); i++){
+        ret += (a[i] == b);
+    }
+    return ret;
+}
+```
+
+```cpp
+std::vector<int> foo4 (const std::vector<int> &a) {
+    std::vector<int> answer = a;
+    for (int i = 0; i < a.size(); i++) {
+        if(a[i] < (a[a.size()-1]*a[a.size()-1])){
+            answer.erase(answer.end()-1);
+        }
+    }
+    return answer;
+}
+```
+
+```cpp
+std::vector<int> foo5 (const std::vector<int> &a, int b) {
+    std::vector<int> ret;
+    for(int i=0; i<a.size(); i++){
+        if(a[i] < b){
+            ret.insert(ret.end(),a[i]);
+        }
+    }
+    return ret;
+}
+```
+
+When you finish, discuss these problems with your teammate. If your teammate hasn’t finished, please help
+them (but without just doing the problems for them).
+
+Once you are both finished, type these examples into your C++ editor, add print statements, and confirm
+your answers are correct. What print statements will be most helpful? In your terminal, instead of running
+just ./a.out try running time ./a.out and reading the real time, which is how long your program took to
+run. How does this change as you increase or decrease each of the data size variables you identified above?
+
+**To complete this checkpoint**, present your work to a TA/mentor.
+
+## Checkpoint 2
+*estimate: TBD*
+
+Write a templated non-member function named remove_matching_elements that takes in two arguments,
+a vector of type Vec<T> and an element of type T, and returns the number of elements that matched the
+argument and were successfully removed from the vector. The order of the other elements should stay
+the same. For example, if v, a Vec<int> object contains 6 elements: 11 22 33 11 55 22 and you call
+remove_matching_elements(v,11), that call should return 2, and v should now contain: 22 33 55 22.
+You should not create a new vector in your function.
+Add several test cases to test_vec.cpp to show that the function works as expected. What is the order
+notation of your solution in terms of n the size of the vector, and e the number of occurences of the input
+element in the vector?
+
+**To complete this checkpoint**, show a TA your debugged solution for remove_matching_elements and
+be prepared to discuss the order notation of the function.
+
+## Checkpoint 3
+*estimate: TBD*
+
+Add a print member function to Vec to aid in debugging. (Note, neither remove_matching_elements nor
+print are not part of the STL standard for vector). You should print the current information stored in the
+variables m_alloc, m_size, and m_data. Use the print function to confirm your remove_matching_elements
+function is debugged. Also, write a test case that calls push_back many, many times (hint, use a for loop!)
+and observe how infrequently re-allocation of the m_data array is necessary.
+To verify your code does not contain memory errors or memory leaks, use Valgrind and/or Dr. Memory on
+your local machine – see instructions on the course webpage: Memory Debugging. Also, submit your code
+to the homework server (in the practice space for lab 4), which is configured to run the memory debuggers
+for this exercise. To verify that you understand the output from Valgrind and/or Dr. Memory, temporarily
+add a simple bug into your implementation to cause a memory error or memory leak.
+
+**To complete this checkpoint**, show a TA your tested & debugged program. Be prepared to demo and
+discuss the Valgrind and/or Dr. Memory output: with and without memory errors and memory leaks AND
+on your local machine and on the homework server.