常见的排序算法C语言实现（—）

void merge(int *A, int q, int mid, int r) {
    int i, j, k;
    int lnum = mid - q + 1;
    int rnum = r - mid;
    int *L = (int *)malloc(sizeof(int)*(lnum + 1));
    int *R = (int *)malloc(sizeof(int)*(rnum + 1));

    for (i = 0; i < lnum; i++) {
        L[i] = A[q + i];
    }
    L[i] = INT_MAX;
    for (i = 0; i < rnum; i++) {
        R[i] = A[mid + i + 1];
    }
    R[i] = INT_MAX;
    i = 0;
    j = 0; //用不同的符号推进三个数组
    k = 0;
    while (k < (lnum + rnum)) {
        if (L[j] > R[i]) {
            A[q + k] = R[i];
            i++;
        } else {
            A[q + k] = L[j];
            j++;
        }
        k++;
    }
    free(L);
    free(R);
    L = NULL;
    R = NULL;
}

void mergesort(int *A, int q, int r) {
    if (q < r) {
        int mid = (q + r) / 2;
        mergesort(A, q, mid);
        mergesort(A, mid + 1, r);
        merge(A, q, mid, r);
    }
}


void split(int *A, int q, int r, int *k) {
    int i, j;
    int x, temp;

    i = q;
    x = A[q];

    for (j = q + 1; j <= r; j++) { 
        if (A[j] <= x) {
            i = i + 1;
            if (i != j) { //此处i指向第一个比x大的值
                temp = A[j];
                A[j] = A[i];
                A[i] = temp;
            }
        }
    }
    temp = A[i]; //此处i指向最后一个比x小的值
    A[i] = A[q];
    A[q] = temp;
    *k = i;
}

void quicksort(int *A, int q, int r) {
    int k;
    if (q < r) {
            split(A, q, r, &k);
            quicksort(A, q, k - 1); //注意这里是k-1,因为是原址排序，上面第k个的位置已经是正确的了
            quicksort(A, k + 1, r);
    }
}

void insertsort(int *A, int num) {
    int i, j;
    int temp;

    for (i = 1; i < num; i++) {
        temp = A[i];
        for (j = i - 1; j >= 0; j--) {
            if (temp > A[j]) { //大于其中一个，前面的肯定比它大
                break;
            }
            else {
                A[j + 1] = A[j];
            }
        }
        A[j + 1] = temp;
    }
}

void selectsort(int *A, int num) {
    int i, j;
    int temp;

    for (i = 0; i < num - 1; i++) { //查找第i小元素
        for (j = i + 1; j < num; j++) {
            if (A[i] > A[j]) {
                temp = A[i];
                A[i] = A[j];
                A[j] = temp;
            }
        }
    }
}

void bubblesort(int *A, int num) {
    int i, j;
    int temp;
    for (i = 0; i < num - 1; i++) { //运行次数
        for (j = 0; j < num -  i - 1; j++) {
            if (A[j] > A[j + 1]) {
                temp = A[j];
                A[j] = A[j + 1];
                A[j + 1] = temp;
            }
        }
    }
}