diff --git a/week03/.clang-format b/week03/.clang-format
new file mode 100644
index 0000000..5bf2f83
--- /dev/null
+++ b/week03/.clang-format
@@ -0,0 +1,2 @@
+BasedOnStyle: LLVM
+IndentWidth: 4
\ No newline at end of file
diff --git a/week03/Makefile b/week03/Makefile
new file mode 100644
index 0000000..9dc6271
--- /dev/null
+++ b/week03/Makefile
@@ -0,0 +1,13 @@
+all: ex1 ex2 ex3 ex4
+
+ex1: ex1.c
+	gcc $< -o $@
+
+ex2: ex2.c
+	gcc $< -o $@ -lm
+
+ex3: ex3.c
+	gcc $< -o $@ -lm
+
+ex4: ex4.c
+	gcc $< -o $@ -lm
diff --git a/week03/a.out b/week03/a.out
new file mode 100755
index 0000000..35d4d40
Binary files /dev/null and b/week03/a.out differ
diff --git a/week03/ex1 b/week03/ex1
new file mode 100755
index 0000000..de6b5ff
Binary files /dev/null and b/week03/ex1 differ
diff --git a/week03/ex1.c b/week03/ex1.c
new file mode 100644
index 0000000..d18c788
--- /dev/null
+++ b/week03/ex1.c
@@ -0,0 +1,33 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+
+int foo(int age) {
+    int result;
+
+    time_t t = time(NULL);
+    result = localtime(&t)->tm_year + 1900 - age;
+
+    return result;
+}
+
+int main() {
+    const int x = 10;
+    const int *q = &x;
+    const int *const p = malloc(sizeof(int) * 5);
+    for (int *i = (int *)p; i < p + 5; ++i) {
+        *i = x;
+        printf("%p%c", i, (i < p + 4 ? ' ' : '\n'));
+    }
+
+    for (int *i = (int *)p; i < p + 5; ++i) {
+        scanf("%d", i);
+    }
+
+    for (int *i = (int *)p; i < p + 5; ++i) {
+        *i = foo(*i);
+        printf("%d%c", *i, (i < p + 4 ? ' ' : '\n'));
+    }
+
+    free((int *)p);
+}
\ No newline at end of file
diff --git a/week03/ex1.sh b/week03/ex1.sh
new file mode 100644
index 0000000..1192c72
--- /dev/null
+++ b/week03/ex1.sh
@@ -0,0 +1,2 @@
+gcc ex1.c -o ex1
+./ex1
\ No newline at end of file
diff --git a/week03/ex2 b/week03/ex2
new file mode 100755
index 0000000..c46d35d
Binary files /dev/null and b/week03/ex2 differ
diff --git a/week03/ex2.c b/week03/ex2.c
new file mode 100644
index 0000000..e956394
--- /dev/null
+++ b/week03/ex2.c
@@ -0,0 +1,28 @@
+#include <math.h>
+#include <stdio.h>
+
+typedef struct Point {
+    float x, y;
+} Point;
+
+float distance(Point p1, Point p2) {
+    return sqrt((p1.x - p2.x) * (p1.x - p2.x) + (p1.y - p2.y) * (p1.y - p2.y));
+}
+
+float area(Point A, Point B, Point C) {
+    return 0.5 * fabsf(A.x * B.y - B.x * A.y + B.x * C.y - C.x * B.y +
+                      C.x * A.y - A.x * C.y);
+}
+
+int main() {
+    Point A = {2.5, 6};
+    Point B = {1, 2.2};
+    Point C = {10, 6};
+
+    float f = distance(A, B);
+	printf("A -- B distance is %f\n", f);
+
+
+	float a = area(A, B, C);
+	printf("Area of triangle ABC is %f\n", a);
+}
\ No newline at end of file
diff --git a/week03/ex2.sh b/week03/ex2.sh
new file mode 100644
index 0000000..c30d5a0
--- /dev/null
+++ b/week03/ex2.sh
@@ -0,0 +1,2 @@
+gcc ex2.c -o ex2 -lm
+./ex2
\ No newline at end of file
diff --git a/week03/ex3 b/week03/ex3
new file mode 100755
index 0000000..71970d2
Binary files /dev/null and b/week03/ex3 differ
diff --git a/week03/ex3.c b/week03/ex3.c
new file mode 100644
index 0000000..72a9232
--- /dev/null
+++ b/week03/ex3.c
@@ -0,0 +1,195 @@
+#include <memory.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+struct Directory;
+struct File;
+
+struct File {
+    int id;
+    unsigned long size;
+    char data[2048];
+    char name[64];
+
+    struct Directory *directory; // The parent directory
+};
+
+struct Directory {
+    int nf;
+    int nd;
+    char path[4096];
+
+    struct File *files[256];
+    struct Directory *directories[8];
+};
+
+typedef struct Directory Directory;
+typedef struct File File;
+
+// Operations on files
+void add_to_file(File *file, const char *content);
+void append_to_file(File *file, const char *content);
+void pwd_file(File *file);
+
+// Operations on directories
+void add_file(File *file, Directory *dir);
+void add_dir(Directory *dir1, Directory *dir2); // given to you
+
+// Helper functions
+void show_dir(Directory *dir);
+void show_file(File *file);
+void show_file_detailed(File *file);
+
+void init_dir(Directory *dir, char *name);
+void init_file(File *file, char *name);
+
+int cur_id = 0;
+
+int main() {
+
+    char content1[] = "int printf(const char * format, ...);";
+    char content2[] = "int main(){printf('Hello World');}";
+    char content3[] = "//This is a comment in C language";
+    char content4[] = "Bourne Again Shell!";
+
+    Directory home, bin, root;
+    init_dir(&root, "/");
+    init_dir(&home, "home");
+    init_dir(&bin, "bin");
+
+    // Example: the path of the folder home is /home
+
+    // Add subdirectories
+    add_dir(&home, &root);
+    add_dir(&bin, &root);
+
+    File bash, ex31, ex32;
+    init_file(&bash, "bash");
+    init_file(&ex31, "ex3_1.c");
+    init_file(&ex32, "ex3_2.c");
+
+    //<WRITE YOUR CODE HERE>
+
+    add_file(&bash, &bin);
+    add_file(&ex31, &home);
+    add_file(&ex32, &home);
+
+    add_to_file(&bash, content4);
+    add_to_file(&ex31, content1);
+    add_to_file(&ex32, content3);
+
+    append_to_file(&ex31, content2);
+
+    show_dir(&root);
+    show_file_detailed(&bash);
+    show_file_detailed(&ex31);
+    show_file_detailed(&ex32);
+
+    pwd_file(&bash);
+    pwd_file(&ex31);
+    pwd_file(&ex32);
+
+    return EXIT_SUCCESS;
+}
+
+// Helper functions
+
+// Displays the content of the Directory dir
+void show_dir(Directory *dir) {
+    printf("\nDIRECTORY\n");
+    printf(" path: %s\n", dir->path);
+    printf(" files:\n");
+    printf("    [ ");
+    for (int i = 0; i < dir->nf; i++) {
+        show_file(dir->files[i]);
+    }
+    printf("]\n");
+    printf(" directories:\n");
+    printf("    { ");
+
+    for (int i = 0; i < dir->nd; i++) {
+        show_dir(dir->directories[i]);
+    }
+    printf("}\n");
+}
+
+// Prints the name of the File file
+void show_file(File *file) { printf("%s ", file->name); }
+
+// Shows details of the File file
+void show_file_detailed(File *file) {
+    printf("\nFILE\n");
+    printf(" id: %d\n", file->id);
+    printf(" name: %s\n", file->name);
+    printf(" size: %lu\n", file->size);
+    printf(" data:\n");
+    printf("    [ %s ]\n", file->data);
+}
+
+// Implementation: Operations on files
+
+// Adds the content to the File file
+void add_to_file(File *file, const char *content) {
+    if (file && content) {
+        strcpy(file->data, content);
+        file->size = strlen(file->data) + 1;
+    }
+}
+
+// Appends the content to the File file
+void append_to_file(File *file, const char *content) {
+    if (file && content) {
+        int sz = strlen(file->data);
+        strcpy(file->data + sz, content);
+        file->size = strlen(file->data) + 1;
+    }
+}
+
+// Prints the path of the File file
+void pwd_file(File *file) {
+    if (file) {
+        printf("%s/%s\n", file->directory->path, file->name);
+    }
+}
+
+// Implementation: Operations on directories
+
+// Adds the File file to the Directory dir
+void add_file(File *file, Directory *dir) {
+    if (file && dir) {
+        dir->files[dir->nf] = file;
+        dir->nf++;
+
+        file->directory = dir;
+    }
+}
+
+// Given to you
+// Adds the subdirectory dir1 to the directory dir2
+void add_dir(Directory *dir1, Directory *dir2) {
+    if (dir1 && dir2) {
+        dir2->directories[dir2->nd] = dir1;
+        dir2->nd++;
+
+        int sz1 = strlen(dir1->path), sz2 = strlen(dir2->path);
+        if (dir2->path[sz2 - 1] == '/') {
+            memmove(dir1->path + sz2, dir1->path, sz1 + 1);
+        } else {
+            memmove(dir1->path + sz2 + 1, dir1->path, sz1 + 1);
+            *(dir1->path + sz2) = '/';
+        }
+        memcpy(dir1->path, dir2->path, sz2);
+    }
+}
+
+void init_dir(Directory *dir, char *name) {
+    dir->nd = dir->nf = 0;
+    strcpy(dir->path, name);
+}
+
+void init_file(File *file, char *name) {
+    file->data[0] = '\0';
+    file->id = cur_id++;
+    strcpy(file->name, name);
+    file->size = 0;
+}
diff --git a/week03/ex3.sh b/week03/ex3.sh
new file mode 100644
index 0000000..c56587a
--- /dev/null
+++ b/week03/ex3.sh
@@ -0,0 +1,2 @@
+gcc ex3.c -o ex3
+./ex3
\ No newline at end of file
diff --git a/week03/ex4 b/week03/ex4
new file mode 100755
index 0000000..ce1f908
Binary files /dev/null and b/week03/ex4 differ
diff --git a/week03/ex4.c b/week03/ex4.c
new file mode 100644
index 0000000..8cc5256
--- /dev/null
+++ b/week03/ex4.c
@@ -0,0 +1,155 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+
+void* aggregate(void* base, size_t size, int n, void* initial_value, void* (*opr)(const void*, const void*));
+
+void* addInt(const void* a, const void* b){
+    int *result = malloc(sizeof(int));
+    *result = *(double*)a + *(int*)b;
+    return result;
+}
+
+void* addDouble(const void* a, const void* b){
+    double *result = malloc(sizeof(double));
+    *result = *(double*)a + *(double*)b;
+    return result;
+}
+
+void* mulInt(const void* a, const void* b){
+    int *result = malloc(sizeof(int));
+    *result = *(double*)a * *(int*)b;
+    return result;
+}
+
+void* mulDouble(const void* a, const void* b){
+    double *result = malloc(sizeof(double));
+    *result = *(double*)a + *(double*)b;
+    return result;
+}
+
+void* meanInt(const void* a, const void* b){
+    double *result = malloc(sizeof(double));
+    *result = (*(double*)a + *(int*)b) / 2.0;
+    return result;
+}
+
+void* meanDouble(const void* a, const void* b){
+    double *result = malloc(sizeof(double));
+    *result = (*(double*)a + *(double*)b) / 2.0;
+    return result;
+}
+
+void* aggregate(void* base, size_t size, int n, void* initial_value, void* (*opr)(const void*, const void*)){
+
+	void* output;
+
+	if (size==sizeof(int)){ // base is a pointer to an integer
+        if (opr == meanInt) {
+            output = malloc(sizeof(double));
+            *(double *)output = *(double*)initial_value;
+            for (int i = 0; i < n; ++i) {
+                double* res = opr(output, ((int*)base) + i);
+                *(double*)output = *res;
+                free(res);
+            }
+        } else {
+            output = malloc(sizeof(int));
+            *(int *)output = *(int*)initial_value;
+            for (int i = 0; i < n; ++i) {
+                int* res = opr(output, ((int*)base) + i);
+                *(int*)output = *res;
+                free(res);
+            }
+        }
+	}else{ // base is a pointer to a double
+        for (int i = 0; i < n; ++i) {
+            double* res = opr(output, ((double*)base) + i);
+            *(double*)output = *res;
+            free(res);
+        }
+	}
+
+	return output;
+}
+
+
+
+
+int main(){
+
+        int* ints = malloc(sizeof(int)*5);
+        double* doubles = malloc(sizeof(double)*5);
+        
+        double *init_mult = malloc(sizeof(double));
+        double *init_add = malloc(sizeof(double));
+        double *init_mean_int = malloc(sizeof(double));
+        double *init_mean_double = malloc(sizeof(double));
+        *init_mult = 1;
+        *init_add = 0;
+        *init_mean_int = ints[0];
+        *init_mean_double = doubles[0];
+
+	// Addition
+	
+        int* result1a;
+        
+        result1a = aggregate(ints, sizeof(int), 5, init_add, addInt);
+        
+        printf("%d\n", *result1a);
+        free(result1a);
+
+	    double* result2a;
+	
+        result1a = aggregate(doubles, sizeof(double), 5, init_add, addDouble);
+	
+        printf("%f\n", *result2a);
+        free(result2a);
+                
+
+	// Multiplication
+	
+        int* result1m;
+        
+        //<WRITE YOUR CODE HERE>;
+        result1m = aggregate(ints, sizeof(int), 5, init_mult, mulInt);
+        
+        printf("%d\n", *result1m);
+        free(result1m);
+
+        double* result2m;
+	    
+        result2m = aggregate(doubles, sizeof(double), 5, init_mult, mulDouble);
+        printf("%f\n", *result2m);
+        free(result2m);
+        
+        
+	// Mean
+	
+        double* result1mean;
+
+        result1mean = aggregate(ints, sizeof(int), 5, init_mean_int, meanInt);
+    
+        printf("%lf\n", *result1mean);
+        free(result1mean);
+
+        double* result2mean;
+	
+        result2mean = aggregate(doubles, sizeof(double), 5, init_mean_double, meanDouble);
+	
+        printf("%f\n", *result2mean);
+        free(result2mean);
+	
+        
+        // free the pointers
+        //<WRITE YOUR CODE HERE>;
+        free(ints);
+        free(doubles);
+        free(init_add);
+        free(init_mult);
+        free(init_mean_double);
+        free(init_mean_int);
+
+
+        return EXIT_SUCCESS;
+}
\ No newline at end of file
diff --git a/week03/ex4.sh b/week03/ex4.sh
new file mode 100644
index 0000000..a8c4a2c
--- /dev/null
+++ b/week03/ex4.sh
@@ -0,0 +1,2 @@
+gcc ex4.c -o ex4
+./ex4
\ No newline at end of file