快速排序与堆排序

快速排序：

稳定的排序，总是将首元素当作枢轴元素，将数组进行划分，然后递归调用，时间复杂度
为nlogn;

#include <iostream>using namespace std;template<typename T>void quickSort(T *array, int n){if(n<=1)return;T *minArray = new T[n];T *maxArray= new T[n];T *equalArray = new T[n];int mi=0,ma=0,me=0;for(int i=0; i<n; i++){if(array[i]<array[0])minArray[mi++] = array[i];else if(array[i]==array[0])equalArray[me++] = array[i];elsemaxArray[ma++] = array[i];}if(mi>1)quickSort<T>(minArray,mi);if(ma>1)quickSort<T>(maxArray,ma);int j=0;for(int i=0; i<mi; i++){array[j++] = minArray[i];}for(int i=0; i<me; i++){array[j++] = equalArray[i];}for(int i=0; i<ma; i++){array[j++] = maxArray[i];}delete[] minArray;delete[] equalArray;delete[] maxArray;}#include <cstdlib>#include <ctime>int main(){int n;while(cin>>n){double *array = new double[n];srand(time(NULL));for(int i=0; i<n; i++){//cin>>array[i];array[i] = rand() % 100;cout << array[i] << " ";}quickSort<double>(array,n);cout << endl;for(int i=0; i<n; i++)cout << array[i] << " ";cout << endl;delete[] array;}return 0;}

堆排序：

不是稳定的排序，不适合小样本集，时间复杂度是nlogn;

#include <iostream>#include <cstdlib>#include <ctime>using namespace std;template<typename T>void swapM(T &a, T &b){T tmp = a;a = b;b = tmp;}template<typename T>void heapify(T *A, int i, int n){int l = 2*i;   // 左儿子int r = 2*i+1; // 右儿子int largest;if (l <= n && A[l] > A[i] )largest = l;elselargest = i;if(r <= n && A[r] > A[largest])largest = r;if( largest != i){swapM<T>(A[i],A[largest]);heapify<T>(A,largest,n);}}// construct a minimum heaptemplate<typename T>void buildHeap(T *A, int n){for(int i=n/2; i>=1; i--)  // i>n/2 是叶子节点，不需要调整heapify<T>(A,i,n);}template<typename T>void heapSort(T *A, int n){buildHeap(A,n);  // <----> buildHeap<T>(A,n);int size = n;for(int i=n; i>=2; i--){swapM<T>(A[1],A[i]);   // 总数将根部元素与尾部元素交换size -= 1;heapify<T>(A,1,size);  // 从剩余元素中获取最大值到根部}}int main(){int n;while(cin>>n){srand(time(NULL));double *heap = new double[n+1];for(int i=1; i<=n; i++)heap[i] = rand()%100;for(int i=1; i<=n; i++)cout << heap[i] << " ";cout << endl;heapSort<double>(heap,n);for(int i=1; i<=n; i++)cout << heap[i] << " ";cout << endl;}return 0;}