参考回答：
归并算法：
#include using namespace std;//将有二个有序数列a[first...mid]和a[mid...last]合并。void __merge(int a[], int first, int mid, int last, int temp[]){int i = first, j = mid + 1;int m = mid, n = last;int k = 0;while (i <= m && j <= n){if (a[i] <= a[j])temp[k++] = a[i++];elsetemp[k++] = a[j++];}while (i <= m)temp[k++] = a[i++];while (j <= n)temp[k++] = a[j++];for (i = 0; i < k; i++)a[first + i] = temp[i];}void __merge_sort(int a[], int first, int last, int temp[]){ if (first < last) { int mid = (first + last) / 2; __merge_sort(a, first, mid, temp); __merge_sort(a, mid + 1, last, temp); __merge(a, first, mid, last, temp); }}bool MergeSort(int a[], int n){ int *p = new int[n]; if (p == NULL) { return false; } else { __merge_sort(a, 0, n - 1, p); delete[] p; return true; }}int main(){ const int LEN = 10; int a[LEN] = { 23, 40, 45, 19, 12, 16, 90, 39, 87, 71 }; cout<<"Before the merge sort, the Array is:"<<endl; for(int i = 0; i < LEN; ++i) { cout<<a[i]<<" "; } cout<<endl; cout<<endl; MergeSort(a, LEN); cout<<"After the merge sort, the Array is:"<<endl; for(int i = 0; i < LEN; ++i) { cout<<a[i]<<" "; } cout<<endl; system("pause"); return 0;}小顶堆：
import java.util.Arrays;public class SmallHeap { public static int[] topN(int[] arr, int n) { int[] list = new int[n]; System.arraycopy(arr, 0, list, 0, n); for (int i = 0; i < n; i++) { int t = i; while (t != 0 && list[parent(t)] > list[t]) { swap(list, t, t = parent(t)); }} for (int i = n, len = arr.length; i < len; i++) { if (arr[i] >= list[0]) { // 置换栈顶 list[0] = arr[i]; // 调整栈顶 int t = 0; while((left(t)<n&&list[t]>list[left(t)])||(right(t)<n&& list[t]>list[right(t)])) { if (right(t) < n && list[right(t)] < list[left(t)]) { swap(list, t, t = right(t)); } else { swap(list, t, t = left(t)); } } } } return list; } private static void swap(int[] list, int i, int j) { int tmp = list[i]; list[i] = list[j]; list[j] = tmp; } private static int parent(int i) { return (i - 1) / 2; } private static int left(int i) { return 2 * i + 1; } private static int right(int i) { return 2 * i + 2; } public static void main(String[] args) { int[] arr = new int[]{56, 30, 71, 18, 29, 93, 44, 75, 20, 65, 68, 34}; System.out.println("原始数组: "); System.out.println(Arrays.toString(arr)); System.out.println("调整后数组: "); System.out.println(Arrays.toString(SmallHeap.topN(arr, 5))); }}
