归并排序-剑指offer

void MergeSort(int a[],int first,int last,int temp[]){
if(first<last){
int mid = (first + last)/2;
MergeSort(a,first,mid,temp);
MergeSort(a,mid+1,last,temp);
MergeArray(a,first,mid,last,temp);
}
}

void MergeArray(int a[],int first,int mid,int last,int temp[]){
//第一个数组
int i = first;int m = mid;
//第二个数组
int j = mid+1;int n = last;
//结果数组
int k = 0;

while(i<=m &&j<=n){
if(a[i]<a[j])
temp[k++] = a[i++];
else
temp[k++] = a[j++];
}
while(i<=m)
temp[k++] = a[i++];

while(j<= n)
temp[k++] = a[j++];
//更新排序后的原数组
for (int i = 0; i < k; i++)
{
a[i+first] = temp[i];
}
}