比较 N个元素 一个一个地插入到一个堆中 以线性时间建立一个堆 已排序、反序、随机输入的运行时间

《数据结构与算法分析——c语言描述》 练习6.11 答案

性能竟然相差两倍。buildheap复杂度是O(N),n次insert是O(NlogN)

#include"binheap.h"
#include<stdlib.h>
#include<stdio.h>
#include<time.h>
#define N 9999999

int RandInt(int i, int j) {
	int temp;
	temp = (int)(i + (1.0*rand() / RAND_MAX)*(j - i));
	return temp;
}

void getRandomInt(int *A, int n) {
	for (int i = 0; i < n; i++) {
		A[i] = i + 1;
	}

	for (int i = 1; i < n; i++) {
		//std::swap(A[i], A[RandInt(0, i)]);  
		int randAdrr = RandInt(0, i);
		int t = A[i];
		A[i] = A[randAdrr];
		A[randAdrr] = t;
	}
}

int randArr[N];
int proper[N];
int reverse[N];

int main() {
	
	getRandomInt(randArr, N);
	
	for (int i = 0; i < N; i++)
		proper[i] = i+1;
	
	for (int i = N - 1; i >= 0; i--)
		reverse[i] = i + 1;

	printf("rand:\n");
	clock_t t1 = clock();
	PriorityQueue h = initialize(N);
	for (int i = 0; i < N; i++) {
		insert(randArr[i], h);
	}
	clock_t t2 = clock();
	printf("%f\n", ((double)t2 - t1) / CLOCKS_PER_SEC);
	destroy(h);


	t1 = clock();
	h = buildHeap(randArr, N);
	t2 = clock();
	printf("%f\n", ((double)t2 - t1) / CLOCKS_PER_SEC);
	destroy(h);



	printf("proper:\n");
	 t1 = clock();
	h = initialize(N);
	for (int i = 0; i < N; i++) {
		insert(proper[i], h);
	}
	 t2 = clock();
	printf("%f\n", ((double)t2 - t1) / CLOCKS_PER_SEC);
	destroy(h);

	t1 = clock();
	h = buildHeap(proper, N);
	t2 = clock();
	printf("%f\n", ((double)t2 - t1) / CLOCKS_PER_SEC);
	destroy(h);

	printf("reverse:\n");
	t1 = clock();
	h = initialize(N);
	for (int i = 0; i < N; i++) {
		insert(reverse[i], h);
	}
	t2 = clock();
	printf("%f\n", ((double)t2 - t1) / CLOCKS_PER_SEC);
	destroy(h);

	t1 = clock();
	h = buildHeap(reverse, N);
	t2 = clock();
	printf("%f\n", ((double)t2 - t1) / CLOCKS_PER_SEC);
	destroy(h);
}