COMP2012H

COMP2012H Homework

Assignment topics:

Project ID	Project Name	Description/Focus
PA1	Calendar	Implement the cal command from Linux.
PA2	A simple text processor	A simple text processor.
PA3	Nonogram	Build a Nonogram solver.
PA4	Factorization (Speed programming)	Factorize large numbers as fast as possible. I had the fastest algorithm in the class.
PA5	Deque ADT: A doubly linked list	Implement a doubly linked list using pointers in C++.
PA6	A mini relational database system	Implement a class for a relational database.
PA7	PortaWordle, a word game	Build a wordle-like game with Qt.
PA8	"The Lord of the Rings" game	Build a game with different game objects and entities using polymorphism.
PA9	Multi-type map using skip list	Implement a skip list with template programming.
PA10	AI digit recognition: Data preprocessing and network testing	Implement image preprocessing algos in C++ using STL.
PA11	A dictionary using trie	Implement a trie using tree algorithms in C++.

Commands

# PA5
g++ -o graded official_grader.cpp Deque.cpp .\Deque_Iterator.cpp; .\graded

# PA6
cd "c:\Users\pinkp\Documents\GitHub\COMP2012H\HW6\"; g++ -Wall -Wextra -pedantic -std=c++11 -o main main.cpp Database.cpp String.cpp Table.cpp; .\main.exe 
C:\Users\pinkp\Documents\GitHub\COMP2012H\DrMemory-Windows-2.3.0-1\bin\drmemory.exe -- C:\Users\pinkp\Documents\GitHub\COMP2012H\HW6\main.exe
Compare-Object (cat output1.txt) (cat output2.txt)

# PA8
C:\Users\pinkp\Documents\GitHub\COMP2012H\DrMemory-Windows-2.3.0-1\bin\drmemory.exe -- C:\Users\pinkp\Documents\GitHub\COMP2012H\HW8\main.exe

# PA9
zip pa9.zip skiplist.tpp object.hpp object.tpp
C:\Users\pinkp\Documents\GitHub\COMP2012H\DrMemory-Windows-2.3.0-1\bin\drmemory.exe -- C:\Users\pinkp\Documents\GitHub\COMP2012H\HW9\main.exe

# PA10
zip PA10.zip dataset.h dataset.cpp train_test.cpp

# PA11
cd "c:\Users\pinkp\Documents\GitHub\COMP2012H\HW11\" ; if ($?) { g++ main.cpp node.cpp dictionary.cpp tasks.cpp -static-libstdc++ -o main } ; if ($?) { .\main }

For redirecting cout output, we can do this:

Add this to main to redirect cout output to a file

std::ofstream out("out.txt");
std::cout.rdbuf(out.rdbuf()); //redirect std::cout to out.txt

then read the file using

Get-Content .\out.txt -Wait -Tail 0

Compare files using

Compare-Object (cat output.txt) (cat output_my.txt)
Compare-Object (cat test_case_output_13.txt) (cat test_case_output_13_my.txt)

For running gdb debugger in VSCode,

visit https://dev.to/talhabalaj/setup-visual-studio-code-for-multi-file-c-projects-1jpi and see HW10/grading for launch.json and tasks.json

Wall of Shame

Mistakes in PA4 (-16.67 marks)

    int num = from;
    ... 
    while (num < to && num >= 2) { 
        // if from = to, then the while loop will immediately exit :D
        // that's why my program won't work for 1 input
        ...
    }

A follow-up on the running time

Jeffrey,

I don't know how I should tell this to you, your program takes only 0.01 or 0.02 (s) in the bonus test case, and if I let it factorize two numbers instead of one, it also passes the edge case. So literally you wrote the fastest program in the whole class. I am sorry that you didn't get the bonus this time. Maybe next time you can let me know in the appeal stage so that we can discuss it. I am sure you will have good performance in the remaining of the semester, for a long time, you were the only one who submitted Qt assignment, and even the designer Dzung is impressed.

Best,
(Censored)

Mistakes in PA5 (-6 bonus marks)

Not checking clarifications before the last day of submissions resulting in wrong deque structure implementation.

[0][1][2][3][4][5][6][7]:8: -> [0][1][2][3]...
if end is at [7] and i call push_back,
end is supposed to point at [0]
but i pointed at :8:
my print function works with this, but TA uses different print function
so their's can't print

Chao's mistake: forgetting to remove a line

Follow-up: PA was regraded and they now accept a different print function

Mistakes in PA7 (-1.875 marks and -0.4 bonus marks)

// incorrect attempt
        for (int i = 0; i < length; i++) {
            correctLetters[guess[i].toLower().toLatin1() - 'a'] = (colors[i] == YELLOW || colors[i] == GREEN);
        }
// correct answer
        correctLetters[guesses[curGuess][i]->getLetter().unicode() - 'a'] |= (colors[i] != GREY);

Mistakes in PA9

1. When implmeneting operator=c(const object& other), remember to check \ if the other object is this:

object& object::operator=(const object& other) {
//  if (this != &other) {
		delete obj_ptr;
		obj_ptr = other.obj_ptr->copy();
//  }
    return *this;
}

2. Tons of memory leak problems that I don't know where to start debugging from.

Mistakes in PA10

When the value stored in a double is an integer \ casting it back into an int will decrease its value by 1

My implementation of nearest neighbour:

int rows = img.size();
int cols = img.at(0).size();
for (int r = 0; r < new_rows; r++) {
	for (int c = 0; c < new_cols; c++) {
		new_img[r][c] = img[(int) 
			((double) (r + 0.5) / new_rows * rows) // get integer part
		][ (int) 
			((double) (c + 0.5) / new_cols * cols) 
		];
	}
}
img = new_img;	

Correct implementations:

new_img[r][c] = img[(int) 
	((float) (r + 0.5) / new_rows * rows) // get integer part
][ (int) 
	((float) (c + 0.5) / new_cols * cols) 
];

or

const float ratio_row = float(img0.size())/new_rows;
const float ratio_col = float(img0[0].size())/new_cols;
for (size_t y=0; y<new_rows; ++y) {
	for (size_t x=0; x<new_cols; ++x) {
		iy = floor(float(ratio_row*(y+0.5)));
		ix = floor(float(ratio_col*(x+0.5)));
		img[y][x] = img0[iy][ix];
	}
}