more work

c/ordered-arrays.c

@@ -0,0 +1,107 @@
+/*
+an ordered array is just a regular array except all elements must be in order,
+so there a few things to note:
+
+1. inserting must respect order
+2. removing must respect order
+3. serching can be made faster with binary search
+ */
+
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+typedef struct FixedOrderedArray {
+    int capacity;
+    int index;  // index next to insert at, arr[index] should be empty
+    int data[];
+} FixedOrderedArray;
+
+FixedOrderedArray *new_fixed_ordered_array(int capacity) {
+    FixedOrderedArray *arr = malloc(sizeof(FixedOrderedArray) + (sizeof(int) * capacity));
+    arr->capacity = capacity;
+    arr->index = 0;
+
+    return (arr);
+}
+
+void fixed_ordered_array_insert(FixedOrderedArray *arr, int val) {
+    if (arr->capacity == arr->index) {
+        fprintf(stderr, "ERROR: array is at capacity, cannot append value\n");
+        exit(1);
+    }
+
+    if (arr->index == 0) {
+        arr->data[0] = val;
+        arr->index++;
+    } else if (val >= arr->data[arr->index - 1]) {
+        arr->data[arr->index] = val;
+        arr->index++;
+    } else if (val <= arr->data[0]) {           // its smallest to add to start
+        for (int i = arr->index; i > 0; i--) {  // shift everything to the right
+            arr->data[i] = arr->data[i - 1];
+        }
+        arr->data[0] = val;
+        arr->index++;
+    } else {  // look for where it belongs
+        for (int i = 0; i < arr->index; i++) {
+            if (arr->data[i] > val) {  // we must shift everything to the right up to this index
+                for (int j = arr->index; j > i; j--) {
+                    arr->data[j] = arr->data[j - 1];
+                }
+                arr->data[i] = val;
+                arr->index++;
+                break;
+            }
+        }
+    }
+}
+
+bool search_fixed_ordered_array(FixedOrderedArray *arr, int val) {
+    if (arr->index == 0) {
+        return (false);
+    }
+
+    if (val < arr->data[0]) {
+        return (false);
+    }
+
+    if (val > arr->data[arr->index - 1]) {
+        return (false);
+    }
+
+    for (int i = 0; i < arr->index; i++) {
+        if (val == arr->data[i]) {
+            return (true);
+        } else if (arr->data[i] > val) {
+            return (false);
+        }
+    }
+    return (false);
+}
+
+void print_array_list(FixedOrderedArray *arr) {
+    printf("[");
+    for (int i = 0; i < arr->index; i++) {
+        printf(" %d ", arr->data[i]);
+    }
+    printf("]\t<capacity: %d; index: %d>\n", arr->capacity, arr->index);
+}
+
+int main() {
+    FixedOrderedArray *arr = new_fixed_ordered_array(5);
+
+    fixed_ordered_array_insert(arr, 10);
+    print_array_list(arr);
+    fixed_ordered_array_insert(arr, 9);
+    print_array_list(arr);
+    fixed_ordered_array_insert(arr, 13);
+    print_array_list(arr);
+    fixed_ordered_array_insert(arr, 11);
+    print_array_list(arr);
+    fixed_ordered_array_insert(arr, 9);
+    print_array_list(arr);
+
+    bool result = search_fixed_ordered_array(arr, 11);
+    printf("the result is %d\n", result);
+}