Merge sort C language implementation

Merge sort typical divide and conquer strategy embodiment, time complexity is O (NLGN), spatial complexity is O (n). is a stable sort.

The following is the C language implementation code.

#define MAX 10000000//p, Q, R is the subscript void merge of the elements (int a[], int p, int q, int r) {    int n1 = q-p + 1;    int n2 = r-q;    int * L = (int *) malloc (sizeof (int) * n1 + 1);    int * R = (int *) malloc (sizeof (int) * n2 + 1);    int I, j, K;    for (i = 0; i < N1; i++) {        L[i] = a[p + i];    }    for (j = 0; J < N2; J + +) {        R[j] = a[q + j + 1];    }    L[i] = MAX;    R[J] = MAX;    i = 0;    j = 0;    for (k = p; k <= R; k++) {        if (L[i] <= r[j]) {            a[k] = l[i];            i++;        } else {            A[k] = r[j];            j + +;}}    } void Merge_sort (int a[], int p, int r) {    if (P < r) {        int q = (p + r)/2;        Merge_sort (A, p, q);        Merge_sort (A, q + 1, r);        Merge (A, p, Q, R);}    }

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Merge sort C language implementation