add hw3 solution

hws/matrix_class/README.txt

@@ -1,7 +1,7 @@
 HOMEWORK 3: MATRIX CLASS
 
 
-NAME:  < insert name >
+NAME:  Jinshan Zhou
 
 
 COLLABORATORS AND OTHER RESOURCES:
@@ -10,13 +10,13 @@ List the names of everyone you talked to about this assignment
 LMS, etc.), and all of the resources (books, online reference
 material, etc.) you consulted in completing this assignment.
 
-< insert collaborators / resources >
+cmath fabs method. Lecture notes about ** pointers and destructors.
 
 Remember: Your implementation for this assignment must be done on your
 own, as described in "Academic Integrity for Homework" handout.
 
 
-ESTIMATE OF # OF HOURS SPENT ON THIS ASSIGNMENT:  < insert # hours >
+ESTIMATE OF # OF HOURS SPENT ON THIS ASSIGNMENT:  14 hr
 
 
 
@@ -27,25 +27,25 @@ number of columns.  You should assume that calling new [] or delete []
 on an array will take time proportional to the number of elements in
 the array.
 
-get
+get -> O(1)
 
-set
+set -> O(1)
 
-num_rows
+num_rows -> O(1)
 
-get_column
+get_column -> O(m)
 
-operator<<
+operator<<  -> O(m*n)
 
-quarter
+quarter  -> O(m*n)
 
-operator==
+operator==  -> O(m*n)
 
-operator!=
+operator!=  -> O(m*n)
 
-swap_rows
+swap_rows  -> O(1)
 
-rref (provided in matrix_main.cpp)
+rref (provided in matrix_main.cpp)  -> O(m^2 * n)
 
 
 
@@ -55,6 +55,17 @@ What tools did you use (gdb/lldb/Visual Studio debugger,
 Valgrind/Dr. Memory, std::cout & print, etc.)?  How did you test the
 "corner cases" of your Matrix class design & implementation?
 
+I used gdb inside VSCode to debug my program. I also used the information
+from the submitty autograder (Dr. Memory) to help me find bugs in my code.
+I basiclly find what's name and function of the methods of Martix class,
+and change my code bit by bit to fit the expected output.
+
 MISC. COMMENTS TO GRADER:  
 (optional, please be concise!)
 
+REFLECTION:
+As the pointer adding up, the complexity of the program will increase.
+I think it is important to understand where do pointers points to and
+delete them when they are not needed anymore. It's quiet tricky and I
+got a lot of memory leaks in my code at first. But the error message in
+Dr. Memory shows which line caused the problem, so I was able to fix it.