归并排序算法

/* * 二路归并排序 * 基本思想 * 当只有一个元素的时候终止排序，超过一个元素的时候，将所有 * 元素分成大致相同的两个集合，然后分别对两个集合进行排序，最后 * 将排好序的集合进行归并 * 稳定性：稳定 * 空间复杂度：O(n) * 时间复杂度:最好O(nlog2n) 最坏O(nlog2n) 平均O(nlog2n) *//* * 归并 */void Merge(int a[], int low, int high){int mid = (low + high) / 2;int d[100] = {0};int i = low, j = mid + 1, k = 0;while(i <= mid && j <= high){if(a[i] <= a[j]){d[k++] = a[i++];}else{d[k++] = a[j++];}}while(i <= mid){d[k++] = a[i++];}while(j <= high){d[k++] = a[j++];}//归并后的结果，拷贝到原数组for(int i=low,k=0; i<=high; i++,k++){a[i] = d[k];}}void MergeSort(int a[], int low, int high){int mid = (low + high) / 2;if(low == high){return;}MergeSort(a, low, mid);MergeSort(a, mid+1, high);Merge(a, low, high);}int main(){int a[] = {3, 8, 15, 7, 21, 6};MergeSort(a, 0, 5);for(int i=0; i<6; i++){cout << a[i] << " ";}cout << endl;system("pause");return 0;}