[數據結構]堆排序的C語言簡單實現

今天突然要用到堆排序，所以按照算法導論的僞代碼簡單實現了一下。
代碼寫得很簡潔，例子也是用算法導論的例子，分別實現了小根堆，大根堆的代碼，可以從小到大排序，也可以從大到小排序

#include <stdio.h>

void MIN_HEAPIFY(int A[], int i, int n);
void MAX_HEAPIFY(int A[], int i, int n);
void BUILD_MIN_HEAR(int A[], int n);
void BUILD_MAX_HEAR(int A[], int n);
void swap(int *a, int *b);

int main()
{
    int N = 10, i;
    int A[] = {-1, 16, 14, 10, 8, 7, 9, 3, 2, 4, 1};
    for (i = 1; i <= N; ++i){
        printf("%d ", A[i]);
    }
    printf("\n");
    /*
    //從小到大排序
    BUILD_MIN_HEAR(A, N);
    for (i = 1; i <= N; ++i){
        printf("%d ", A[i]);
    }
    printf("\n");
    while (N >= 1){
        printf("%d ", A[1]);
        A[1] = A[N];
        N--;
        BUILD_MIN_HEAR(A, N);
    }
    */
    //從大到小排序
    BUILD_MAX_HEAR(A, N);
    for (i = 1; i <= N; ++i){
        printf("%d ", A[i]);
    }
    printf("\n");
    while (N >= 1){
        printf("%d ", A[1]);
        A[1] = A[N];
        N--;
        BUILD_MAX_HEAR(A, N);
    }
    return 0;
}

void BUILD_MIN_HEAR(int A[], int n){
    int i;
    for (i = n / 2; i >= 1; --i){
        MIN_HEAPIFY(A, i, n);
    }
}

void BUILD_MAX_HEAR(int A[], int n){
    int i;
    for (i = n / 2; i >= 1; --i){
        MAX_HEAPIFY(A, i, n);
    }
}

void MIN_HEAPIFY(int A[], int i, int n){
    int l = i * 2;  //左孩子下標
    int r = i * 2 + 1;  //右孩子下標
    int min = i;
    if (l <= n && A[l] < A[i]){
        min = l;
    }
    if (r <= n && A[r] < A[min]){
        min = r;
    }
    if (min != i){
        swap(&A[i], &A[min]);
        MIN_HEAPIFY(A, min, n);
    }
}

void MAX_HEAPIFY(int A[], int i, int n){
    int l = i * 2;  //左孩子下標
    int r = i * 2 + 1;  //右孩子下標
    int large = i;
    if (l <= n && A[l] > A[i]){
        large = l;
    }
    if (r <= n && A[r] > A[large]){
        large = r;
    }
    if (large != i){
        swap(&A[i], &A[large]);
        MAX_HEAPIFY(A, large, n);   //遞歸，調整交換後的結點
    }
}

void swap(int *a, int *b){  //交換元素
    int temp = *b;
    *b = *a;
    *a = temp;
}