用OpenMP语言编写程序，排序数组a，先将数组a分为p份，每个线程调用sort函数排序一份，然后调用merge函数将p个有序序列归并

#include <stdio.h>
#include <stdlib.h>
#include <omp.h>

#define MAX_SIZE 1000000

void merge(int a[], int l, int m, int r){
int i, j, k;
int n1 = m - l + 1;
int n2 = r - m;

int L[n1], R[n2];

for (i = 0; i < n1; i++)
L[i] = a[l + i];
for (j = 0; j < n2; j++)
R[j] = a[m + 1 + j];

i = 0;
j = 0;
k = l;
while (i < n1 && j < n2) {
if (L[i] <= R[j]) {
a[k] = L[i];
i++;
}
else {
a[k] = R[j];
j++;
}
k++;
}

while (i < n1) {
a[k] = L[i];
i++;
k++;
}

while (j < n2) {
a[k] = R[j];
j++;
k++;
}
}

void mergeSort(int a[], int l, int r){
if (l < r) {
int m = l + (r - l) / 2;

mergeSort(a, l, m);
mergeSort(a, m + 1, r);

merge(a, l, m, r);
}
}

void parallelSort(int* a, int n, int p){
int size = n/p;
#pragma omp parallel num_threads(p)
{
int tid = omp_get_thread_num();
int start = tid * size;
int end = start + size - 1;
if(tid == p-1) end = n-1;

mergeSort(a, start, end);
}

int i, j = 0;
for(i = 1; i < p; i++){
int* temp = (int*) malloc(size * sizeof(int));
int k = i * size;
int idx = 0;
while(j < k && j < n){
temp[idx++] = a[j++];
}

k = (i+1) * size;
while(j < k && j < n){
temp[idx++] = a[j++];
}

merge(a, 0, (i-1)*size+(size/2), i*size+(size/2)-1);
}
}

int main(){
int n, p, i;
int a[MAX_SIZE];

printf("Enter the number of elements: ");
scanf("%d", &n);

printf("Enter the elements: ");
for(i = 0; i < n; i++){
scanf("%d", &a[i]);
}

printf("Enter the number of threads: ");
scanf("%d", &p);

parallelSort(a, n, p);

printf("Sorted array: ");
for(i = 0; i < n; i++){
printf("%d ", a[i]);
}
printf("\n");

return 0;
}