TD1_DEV51_Qualite_Algo/qiktri.c

#include "qiktri.h"

static void insertion_sort(int* array, int low, int high)
{
    for (int i = low + 1; i <= high; i++)
    {
        int key = array[i];
        int j = i - 1;
        while (j >= low && array[j] > key)
        {
            array[j + 1] = array[j];
            j--;
        }
        array[j + 1] = key;
    }
}

static int partition_qiktri(int* array, int low, int high)
{
    int mid = low + (high - low) / 2;

    // médiane de trois pour choisir un bon pivot
    if (array[mid] < array[low]) {
        int tmp = array[mid]; array[mid] = array[low]; array[low] = tmp;
    }
    if (array[high] < array[low]) {
        int tmp = array[high]; array[high] = array[low]; array[low] = tmp;
    }
    if (array[mid] < array[high]) {
        int tmp = array[mid]; array[mid] = array[high]; array[high] = tmp;
    }

    int pivot = array[high];  
    int i = low - 1;
    for (int j = low; j < high; j++)
    {
        if (array[j] <= pivot)
        {
            i++;
            int temp = array[i];
            array[i] = array[j];
            array[j] = temp;
        }
    }

    int temp = array[i + 1];
    array[i + 1] = array[high];
    array[high] = temp;

    return i + 1;
}

void qiktri(int* array, int low, int high)  // ⬅️ plus de "static"
{
    while (low < high)
    {
        if (high - low < 16)
        {
            insertion_sort(array, low, high);
            break;
        }

        int pi = partition_qiktri(array, low, high);

        if (pi - low < high - pi)
        {
            qiktri(array, low, pi - 1);
            low = pi + 1;
        }
        else
        {
            qiktri(array, pi + 1, high);
            high = pi - 1;
        }
    }
}