heap_sort

#include <stdio.h>

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

void fill_array(int* mas, int N, int a, int b){
    int i;
    for (i = 0; i < N; ++i)
        mas[i] = rand()%(b-a+1)+a;
}

void shift_down(int* mas, int i, int j){
    int left, right, max_child, temp;
    left = 2*i+1;
    right = left + 1;
    max_child = left;
    while ( max_child < j ) {
        if ( right < j ){
            if ( mas[left] < mas[right] )
                max_child = right;
            if ( mas[i] < mas[max_child] )
                swap (&mas[i], &mas[max_child]);
        } else break;
        i = max_child;
        left = 2*i+1;
        right = left+1;
        max_child = left;
    }
}

void heap_sort(int* mas, int N){
    int i;
    for (i = N/2-1; i >= 0; --i)
        shift_down(mas, i, N);

    for (i = N-1; i > 0; --i){
        swap(mas, &mas[i]);
        shift_down(mas, 0, i);
    }
}

void print_array(int* mas, int N){
    int i;
    for (i = 0; i < N; ++i)
        printf("%d ", mas[i]);
    printf("\n");
}

int main()
{
    unsigned const int N = 20;
    int a[N];
    fill_array(a, N, -50, 50);
    print_array(a, N);
    heap_sort(a, N);
    print_array(a, N);
}