more algos

c/arraylist.c

@@ -0,0 +1,61 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+typedef struct ArrayList {
+    int capacity;
+    int index;
+    int data[];
+} ArrayList;
+
+ArrayList* new_arraylist(int cap) {
+    ArrayList* arr = malloc(sizeof(ArrayList) + cap * sizeof(int));
+    arr->capacity = cap;
+    arr->index = 0;
+    for (int i = 0; i < cap; i++) {
+        arr->data[i] = 0;
+    }
+
+    return arr;
+}
+
+void push_to_array(ArrayList* s, int v) {
+    if (s->index == s->capacity) {
+        printf("you attempted to insert %d, but array is at capacity cannot add mode values\n", v);
+    } else {
+        s->data[s->index] = v;
+        s->index++;
+    }
+}
+
+void pop_from_array(ArrayList* s) {
+    if (s->index == 0) {
+        printf("there is nothing to remove!\n");
+    } else {
+        s->index--;
+    }
+}
+
+void grow_array_list(ArrayList* s, int amount) {
+}
+
+void print_array_list(ArrayList* arr) {
+    printf("[");
+    for (int i = 0; i < arr->index; i++) {
+        printf(" %d ", arr->data[i]);
+    }
+    printf("]\n");
+}
+
+int main() {
+    ArrayList* a = new_arraylist(5);
+    push_to_array(a, 10);
+    push_to_array(a, 11);
+    push_to_array(a, 12);
+    push_to_array(a, 12);
+    push_to_array(a, 12);
+    push_to_array(a, 12);
+    push_to_array(a, 12);
+    pop_from_array(a);
+    push_to_array(a, 155);
+    print_array_list(a);
+}

c/qs.c

@@ -0,0 +1,49 @@
+#include <stdio.h>
+
+// partition takes an array and a low and hi values and partitions the array
+// by rearrating and placing everything smaller then the pivot point to the left
+// of it and everything greater than it on the right
+int partition(int arr[], int lo, int hi) {
+    int pivot_value = arr[hi];
+    int idx = -1;  // this will keep track of current location of values less then the pivot
+
+    for (int i = 0; i < hi; i++) {
+        if (arr[i] <= pivot_value) {
+            idx++;
+
+            // if less than the pivot then swap the ith value with the current idx
+            int tmp = arr[i];
+            arr[i] = arr[idx];
+            arr[idx] = tmp;
+        }
+    }
+
+    // after the iteration we still need to reposition our pivot_value to the last
+    // position that idx was after the for loop ends, this will mean that everything
+    // to left of idx will be less than the pivot point
+    idx++;
+    arr[hi] = arr[idx];
+    arr[idx] = pivot_value;
+}
+
+void quick_sort(int arr[], int lo, int hi) {
+    if (lo >= hi) {
+        printf("error!");
+    }
+
+    int current_pivot = partition(arr, lo, hi);
+    quick_sort(arr, lo, current_pivot - 1);
+    quick_sort(arr, current_pivot + 1, hi);
+}
+
+int main() {
+    int array_len = 5;
+    int arr[5] = {5, 4, 3, 2, 1};
+    quick_sort(arr, 0, array_len);
+
+    printf("[ ");
+    for (int i = 0; i < array_len; i++) {
+        printf("%d ", arr[i]);
+    }
+    printf("]\n");
+}

c/stack.c

@@ -39,11 +39,12 @@ Stack* new_stack() {
     return (s);
 }
 
-bool pop(Stack* s) {
+int pop(Stack* s) {
     if (s->length == 0) {
         return false;
     } else {
         Node* n = s->head;
+        int   val = n->value;
         if (s->length == 1) {
             s->head = NULL;
         } else {
@@ -51,7 +52,7 @@ bool pop(Stack* s) {
         }
         free(n);
         s->length--;
-        return true;
+        return val;
     }
 }
 
@@ -103,32 +104,23 @@ int main() {
     printf("the value at the top of the stack is: %d\n", peek(s));
     printf("the length of the stack is: %d\n", s->length);
 
-    // bool res = pop(s);
-    // printf("the value at the top of the stack is: %d\n", peek(s));
-    // printf("the length of the stack is: %d\n", s->length);
+    printf("the value at the top of the stack is: %d\n", pop(s));
+    printf("the length of the stack is: %d\n", s->length);
 
-    // res = pop(s);
-    // printf("the value at the top of the stack is: %d\n", peek(s));
-    // printf("the length of the stack is: %d\n", s->length);
+    printf("the value at the top of the stack is: %d\n", pop(s));
+    printf("the length of the stack is: %d\n", s->length);
 
-    // res = pop(s);
-    // printf("the value at the top of the stack is: %d\n", peek(s));
-    // printf("the length of the stack is: %d\n", s->length);
+    printf("the value at the top of the stack is: %d\n", pop(s));
+    printf("the length of the stack is: %d\n", s->length);
 
-    // res = pop(s);
-    // printf("the value at the top of the stack is: %d\n", peek(s));
-    // printf("the length of the stack is: %d\n", s->length);
-    // res = pop(s);
-    // printf("the value at the top of the stack is: %d\n", peek(s));
-    // printf("the length of the stack is: %d\n", s->length);
-    // res = pop(s);
-    // printf("the value at the top of the stack is: %d\n", peek(s));
-    // printf("the length of the stack is: %d\n", s->length);
-    // res = pop(s);
-    // printf("the value at the top of the stack is: %d\n", peek(s));
-    // printf("the length of the stack is: %d\n", s->length);
-
-    delete_stack(s);
+    printf("the value at the top of the stack is: %d\n", pop(s));
+    printf("the length of the stack is: %d\n", s->length);
+    printf("the value at the top of the stack is: %d\n", pop(s));
+    printf("the length of the stack is: %d\n", s->length);
+    printf("the value at the top of the stack is: %d\n", pop(s));
+    printf("the length of the stack is: %d\n", s->length);
+    printf("the value at the top of the stack is: %d\n", pop(s));
+    printf("the length of the stack is: %d\n", s->length);
 
     return (0);
 }