合併排序演算法實例程式（C語言）

合併排序演算法C語言實例程式，如下圖所示：

#include <stdio.h>

int a[20], b[20], n;

void merging(int low, int mid, int high) {
   int l1,l2,i;

   for(l1 = low, l2 = mid + 1, i = low; l1 <= mid && l2 <= high; i++){
      if(a[l1] <= a[l2])
         b[i] = a[l1++];
      else
         b[i] = a[l2++];
   }

   while(l1 <= mid)
      b[i++] = a[l1++];

   while(l2 <= high)
      b[i++] = a[l2++];

   for(i = low; i <= high; i++)
      a[i] = b[i];
}

void sort(int low,int high) {
   int mid;

   if(low < high) {
      mid = (low+high) / 2;
      sort(low, mid);
      sort(mid+1, high);
      merging(low, mid, high);
   }
   else {
      return;
   }

}

int main() {
   int i;

   printf("Enter N ");
   scanf("%d",&n);

   printf("Enter elements\n");

   for(i = 1; i <= n; i++)
      scanf("%d",& a[i]);

   sort(1,n);

   printf("After sorting\n");

   for(i = 1; i <= n; i++)
      printf("%d\n", a[i]);
}