added sagas problems (#258)

Author: Allynixtor

data/course-revision/1511-23T3/2d_malloc.mdx

@@ -47,7 +47,7 @@ $ ./2d_malloc 10 10
 
 When you think your program is working, you can use CSE autotest to test your solution.
 
-```bash:~/1521-revision/2d_malloc
+```bash:~/1511-revision/2d_malloc
 $ 1511 csesoc-autotest 2d_malloc
 ```
 

data/course-revision/1511-23T3/atoi.mdx

@@ -0,0 +1,49 @@
+---
+title: atoi
+desc: Implement the C stdlib function atoi
+class: COMP1511
+difficulty: 2
+---
+
+# atoi
+
+Your task is to implement the C Standard Library function `atoi`. `atoi` takes in a `const char *` that is guaranteed to be a numerical string, e.g. `"123"`, and returns the numerical form of that string.
+
+For example,
+
+```
+atoi("123") -> 123
+atoi("19") -> 19
+```
+
+Your function should take in command line arguments (which are guaranteed to be numerical), and use your implementation of `atoi` to convert them into a number, and print it out.
+
+Furthermore, once you have printed out all the command line arguments, you should print out the sum and product of all these arguments.
+
+The output from your program should look **exactly** like this:
+
+```bash:~/1511-revision/atoi
+$ dcc atoi.c -o atoi
+$ ./atoi 3 2
+3
+2
+5 6
+```
+
+## Assumptions/Restrictions/Clarifications
+
+It is guaranteed that the command lines argument given in the autotest are numerical.
+
+You should not use the library implementation of `atoi` as that defeats the whole purpose of this exercise.
+
+## CSE Autotest
+
+When you think your program is working, you can use CSE autotest to test your solution.
+
+```bash:~/1511-revision/atoi
+$ 1511 csesoc-autotest atoi
+```
+
+## Solution
+
+You can view the solution code to this problem [here](https://github.com/Allynixtor/comp1511-23T3-problems/blob/main/solutions/atoi/solution.c).

data/course-revision/1511-23T3/strcmp.mdx

@@ -0,0 +1,49 @@
+---
+title: strcmp
+desc: Implement the C stdlib function strcmp
+class: COMP1511
+difficulty: 2
+---
+
+# strcmp
+
+Your task is to implement the C Standard Library function `strcmp`. `strcmp` takes in two `const char *` and returns an integer depending on the differences between the two strings.
+
+`strcmp` works by sequentially going through both strings and comparing each character.
+If `char 1` < `char 2`, then we would return `-1`.
+If `char 1 > char 2`, then we would return `1`.
+
+However, If both strings equal each other, then we would return `0`.
+
+For example,
+
+```
+strcmp("hi", "hi") -> 0
+strcmp("a", "b") -> -1
+```
+
+The output from your program should look **exactly** like this:
+
+```bash:~/1511-revision/strcmp
+$ dcc strcmp.c -o strcmp
+$ ./strcmp "hello" "hello"
+0
+```
+
+## Assumptions/Restrictions/Clarifications
+
+You should not use the library implementation of `strcmp` as that defeats the whole purpose of this exercise.
+
+It is guaranteed that your function is only expected to return `0`, `1`, and `-1`.
+
+## CSE Autotest
+
+When you think your program is working, you can use CSE autotest to test your solution.
+
+```bash:~/1511-revision/strcmp
+$ 1511 csesoc-autotest strcmp
+```
+
+## Solution
+
+You can view the solution code to this problem [here](https://github.com/Allynixtor/comp1511-23T3-problems/blob/main/solutions/strcmp/solution.c).

data/course-revision/1511-23T3/strlen.mdx

@@ -0,0 +1,36 @@
+---
+title: strlen
+desc: Implement the C stdlib function strlen
+class: COMP1511
+difficulty: 2
+---
+
+# strlen
+
+Your task is to implement the C Standard Library function `strlen`. `strlen` takes in a `const char *` and returns an integer that is the length of the given string,
+
+````
+The output from your program should look **exactly** like this:
+```bash:~/1511-revision/strlen
+$ dcc strlen -o strlen
+$ ./strlen "hi"
+2
+````
+
+## Assumptions/Restrictions/Clarifications
+
+You should not use the library implementation of `strlen` as that defeats the whole purpose of this exercise.
+
+Note that `strlen` does not count the null terminator `\0` as part of a string's length.
+
+## CSE Autotest
+
+When you think your program is working, you can use CSE autotest to test your solution.
+
+```bash:~/1511-revision/strlen
+$ 1511 csesoc-autotest strlen
+```
+
+## Solution
+
+You can view the solution code to this problem [here](https://github.com/Allynixtor/comp1511-23T3-problems/blob/main/solutions/strlen/solution.c).