#include "sort.h"

#include <cstring>

void swap(char **a, char **b) {
    char *temp = *a;
    *a = *b;
    *b = temp;
}

int partition(char **arr, const int first, const int last)
{
    const char *pivot = arr[last];

    int i = first;
    for (int j = first; j < last; j++) {
        if (strcmp(arr[j], pivot) <= 0) {
            swap(&arr[i], &arr[j]);
            i++;
        }
    }
    swap(&arr[i], &arr[last]);
    return (i);
}

void quick_sort(char **arr, const size_t length) {
    if (length <= 1) {
        return;
    }
    int low = 0, high = length - 1;
    int stack[high - low + 1];
    int top = -1;
    stack[++top] = low;
    stack[++top] = high;
    while (top >= 0) {
        high = stack[top--];
        low = stack[top--];
        const int pivot_pos = partition(arr, low, high);

        if (pivot_pos - 1 > low) {
            stack[++top] = low;
            stack[++top] = pivot_pos - 1;
        }

        if (pivot_pos + 1 < high) {
            stack[++top] = pivot_pos + 1;
            stack[++top] = high;
        }
    }
}