归并排序

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void merge1(int *a,int left,int mid,int right){     int n1=mid-left+1;     int n2=right-mid;     int *arr1=new int[n1];     int *arr2=new int[n2];     for(int i=0;i<n1;i++)         arr1[i]=a[left+i];     for(int i=0;i<n2;i++)         arr2[i]=a[mid+i+1];     int i=0,j=0,k=left;     while(i<n1&&j<n2){         if(arr1[i]<arr2[j])             a[k++]=arr1[i++];         else             a[k++]=arr2[j++];     }       while(i<n1){         a[k++]=arr1[i++];     }     while(j<n2){         a[k++]=arr2[j++];     } } void merge2(int *a,int left,int mid,int right){     int i=left;     int j=mid+1;     int *temp=new int[right-left+1];     int t=0;     while(i<=mid&&j<=right)         if(a[i]<=a[j])             temp[t++]=a[i++];         else             temp[t++]=a[j++];     while(i<=mid)         temp[t++]=a[i++];     while(j<=right)         temp[t++]=a[j++];     t=0;     while(left<=right)         a[left++]=temp[t++]; }   void mergeSort(int *a,int left,int right){     if(left<right){         int mid=(left+right)/2;         mergeSort(a,left,mid);         mergeSort(a,mid+1,right);                 merge1(a,left,mid,right);              //merge2(a,left,mid,right);     } }