# A non-recursive algorithm for merging sort

Source: Internet
Author: User

Algorithm idea:

First assume length=1; Indicates that the adjacent 2 elements are sorted first. A[0] and a[1],a[2] and a[3] ...... A[n-2] and A[n-1] (N is even hypothesis)

Then Length=2;a[0]a[1] is an ordered sequence, with a[2]a[3] to merge 2 ordered sequences.

In turn.

`  voidMerge_pass (ElementType a[],elementtype temp[],intNintlength) { inti,j;  for(i=0; i<n-2*length;i+=2*length) Merge1 (A,temp,i,i+length,i+length*2-1); if(i+length<N) Merge1 (a,temp,i,i+length,n-1);//Super ErrorElse    {         for(j=i;j<n;j++) Temp[j]=A[j]; }} voidMerge_sort (ElementType a[],intN) {intlength; ElementType*Temp; Temp= (ElementType *)mallocNsizeof(ElementType)); Length=1; if(temp!=NULL) {          while(length<N) {merge_pass (a,temp,n,length); Length=length*2;             Merge_pass (temp,a,n,length); Length=length*2; }     }     Elseprintf ("error\n"); } voidMerge1 (ElementType a[],elementtype temp[],intLeft,intRight,intrightend) {    intTemp,i, Leftend,count; Leftend=right-1; Count=rightend-left+1; Temp=Left ;  while(left<=leftend&& right<=rightend) {        if(a[left]<=A[right]) Temp[temp++]=a[left++]; Elsetemp[temp++]=a[right++]; }     while(left<=leftend) Temp[temp++]=a[left++];  while(right<=rightend) Temp[temp++]=a[right++]; }`

Error Analysis:

`Merge1 (a,temp,i,i+length,n);There should be n elements, and the subscript for the last element is n-1!!!!!!!!!!!!!`

Non-recursive algorithm for merge sort

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