题目：
重写MERGE过程，使其不使用标记，而是在数组L或R将其所有元素复制回A然后将另一个数组的其余部分复制回A时停止。

伪代码

MERGE(A, p, q, r)
  n1 = q - p + 1
  n2 = r - q
  let L[1..n₁] and R[1..n₂] be new arrays
  for i = 1 to n₁
      L[i] = A[p + i - 1]
  for j = 1 to n₂
      R[j] = A[q + j]
  i = 1
  j = 1
  for k = p to r
      if i > n₁
          A[k] = R[j]
          j = j + 1
      else if j > n₂
          A[k] = L[i]
          i = i + 1
      else if L[i] ≤ R[j]
          A[k] = L[i]
          i = i + 1
      else
          A[k] = R[j]
          j = j + 1

代码

#include  <stdio.h>

void merge（int A []，int p，int q，int r）{
     int i，j，k;

    int n1 = q  -  p + 1 ;
    int n2 = r  -  q;

    int L [n1];
    int R [n2];

    for（i = 0 ; i <n1; i ++）
        L [i] = A [p + i];
    for（j = 0 ; j <n2; j ++）
        R [j] = A [q + j + 1 ];

    for（i = 0，j = 0，k = p; k <= r; k ++）{
         if（i == n1）{
            A [k] = R [j ++];
        } else  if（j == n2）{
            A [k] = L [i ++];
        } else  if（L [i] <= R [j]）{
            A [k] = L [i ++];
        } else {
            A [k] = R [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）;
        合并（A，p，q，r）;
    }
}