Vector2.c

#include <stdio.h>
#include <stdlib.h>

#define COEFFIECIENT 2

typedef struct {
  int capacity, used_size;
  int *data;
} Vector;

void vec_init(Vector *v, int capacity) {
  if (capacity <= 0) {
    return;
  }

  v->data = malloc(capacity * sizeof(int));
  v->capacity = capacity;
  v->used_size = 0;
}

void vec_push(Vector *V, int element) {
  if (V->used_size == V->capacity) {
    V->data = realloc(V->data, V->capacity * COEFFIECIENT * sizeof(int));
    V->capacity *= COEFFIECIENT;
  }

  V->data[V->used_size] = element;
  V->used_size++;
}

void vec_pop(Vector *V) {
  if (V->used_size == 0 || V->capacity == 0)
    return;

  V->used_size--;
  if (V->used_size <= V->capacity / COEFFIECIENT) {
    V->data = realloc(V->data, (V->capacity / COEFFIECIENT) * sizeof(int));
    V->capacity /= COEFFIECIENT;
  }
}

void vec_delete(Vector *V) { free(V->data); }

int vec_get(Vector *V, int index) { return (V->data)[index]; }

// -------------------------------

typedef struct {
  int capacity, used_size;
  Vector *vectors;
} Container;

void container_init(Container *C, int capacity) {
  C->vectors = malloc(sizeof(Vector) * capacity);
  C->capacity = capacity;
  C->used_size = 0;
}

// ASSUMES V's ownership!!!
void container_push(Container *C, const Vector *V) {
  if (C->used_size == C->capacity) {
    C->vectors =
        realloc(C->vectors, C->capacity * COEFFIECIENT * sizeof(Vector));
    C->capacity *= COEFFIECIENT;
  }

  *(C->vectors + C->used_size++) = *V;
}

void container_pop(Container *C) {
  if (C->used_size == 0 || C->capacity == 0)
    return;

  vec_delete(C->vectors + --(C->used_size));

  if (C->used_size <= C->capacity / COEFFIECIENT) {
    C->vectors =
        realloc(C->vectors, (C->capacity / COEFFIECIENT) * sizeof(Vector));
    C->capacity /= COEFFIECIENT;
  }
}

Vector *container_get(Container *C, int index) { return C->vectors + index; }

void container_delete(Container *C) {
  for (int i = 0; i < C->used_size; i++)
    vec_delete(container_get(C, i));
  free(C->vectors);
}

int main() {
  Container C;
  container_init(&C, 1);

  for (int i = 0; i < 5; i++) {
    Vector V;
    vec_init(&V, 10);
    for (int j = 0; j < 99; j++) {
      vec_push(&V, j);
    }
    container_push(&C, &V);

  }

  container_pop(&C);

  for (int i = 0; i < 4; i++) {
    for (int j = 0; j < 9; j++) {
      printf("%d ", vec_get(container_get(&C, i), j));
    }
    printf("\n");
  }

  vec_pop(container_get(&C, 2));

  container_delete(&C);

  return 0;
}