赞
踩
希尔排序(Shell Sort)是一种基于插入排序的算法,由Donald Shell于1959年提出。希尔排序的基本思想是将待排序的序列划分成若干个子序列,分别进行插入排序,待整个序列中的记录基本有序时,再对全体记录进行一次直接插入排序。
function shellSort(arr):
n = length(arr)
gap = n / 2
while gap > 0:
for i = gap; i < n; i++:
temp = arr[i]
j = i
while j >= gap and arr[j - gap] > temp:
arr[j] = arr[j - gap]
j -= gap
arr[j] = temp
gap = gap / 2
return arr
尽管希尔排序在理论上的时间复杂度不如一些现代排序算法,但在实际应用中,尤其是在数据量不是非常大时,希尔排序由于其低廉的实现成本和较好的性能,仍然是一个可行的选择。此外,对于一些特定数据结构和数据集,通过精心设计的间隔序列,希尔排序可以展现出比传统插入排序更好的性能。
希尔排序的时间复杂度分析相对复杂,因为它依赖于间隔序列的选择。以下是几种不同情况下的时间复杂度分析
在最坏的情况下,希尔排序的时间复杂度为 (O(n^2))。这是因为在最坏情况下,每次插入排序操作都需要移动其他元素。由于希尔排序是通过比较间隔序列中的元素来进行的,因此存在一种情况,其中间隔序列被设置为非常小的值(例如1),这实际上将希尔排序转换为普通的插入排序。
在平均情况下,希尔排序的时间复杂度通常被认为介于 (O(n^{1.3} \log n)) 到 (O(n^{2.25} \log n)) 之间。这是因为在平均情况下,插入排序的效率得到了提高,因为每次插入操作不需要移动所有的元素。
在最佳情况下,希尔排序的时间复杂度可以达到 (O(n \log^2 n))。这是当间隔序列被设计得非常好的情况下,例如使用Sedgewick间隔序列时。在这种情况下,每次插入操作需要移动的元素数量较少,因此整体效率较高。
希尔排序的空间复杂度为 (O(1))。这是因为希尔排序是原地排序算法,除了输入数组本身之外,它只需要一个很小的常数空间来存储间隔序列和临时变量。因此,希尔排序不需要额外的内存空间来完成排序。
由于希尔排序的时间复杂度分析依赖于间隔序列的选择,没有统一的数学证明来确定其时间复杂度。上述的时间复杂度是基于实验和观察得出的,而不是精确的数学证明。然而,对于特定的间隔序列,如Sedgewick间隔序列,已经有一些研究表明它在平均和最佳情况下的时间复杂度。
总的来说,希尔排序的时间复杂度分析是实验性的,而不是理论性的。在实际应用中,选择合适的间隔序列可以显著提高希尔排序的性能,使其在某些情况下比传统的插入排序更有效率。
def shell_sort(arr):
n = len(arr)
gap = n // 2
while gap > 0:
for i in range(gap, n):
temp = arr[i]
j = i
while j >= gap and arr[j - gap] > temp:
arr[j] = arr[j - gap]
j -= gap
arr[j] = temp
gap //= 2
void shellSort(int arr[], int n) {
for (int gap = n/2; gap > 0; gap /= 2) {
for (int i = gap; i < n; i += 1) {
int temp = arr[i];
int j;
for (j = i; j >= gap && arr[j - gap] > temp; j -= gap) {
arr[j] = arr[j - gap];
}
arr[j] = temp;
}
}
}
template <typename T> void shellSort(vector<T> &arr) { // n is the size of the array int n = arr.size(); // gap is the difference between the current position and the gap position for (int gap = n / 2; gap > 0; gap /= 2) { // i is the current position for (int i = gap; i < n; ++i) { // temp is the current element T temp = arr[i]; // j is the gap position int j; // loop from i to gap and swap the elements if the gap position is greater than the current element for (j = i; j >= gap && arr[j - gap] > temp; j -= gap) { arr[j] = arr[j - gap]; } // swap the current element with the gap position arr[j] = temp; } } }
除了这些基于间隔序列优化的方法,还有一些其他的工作致力于改进希尔排序的性能,例如通过减少比较和交换操作来提高效率。然而,尽管这些方法可能对特定数据集或特定情况有所帮助,但它们并没有产生新的希尔排序变种,而是在原有算法基础上的一些改进。希尔排序的时间复杂度优化主要集中在间隔序列的选择和实现细节的优化上。通过选择合适的间隔序列和优化实现,可以在一定程度上提高希尔排序的性能。然而,需要注意的是,希尔排序的时间复杂度仍然在最坏情况下是 (O(n^2)),这使得它在处理大数据集时可能不如其他更高效的排序算法。
function hibbardShellSort(arr):
n = length(arr)
k = 1
while (2^k - 1) < n:
k += 1
for gap = 2^(k-1) - 1; gap > 0; gap = (gap / 2) - 1:
for i = gap; i < n; i++:
temp = arr[i]
j = i
while j >= gap and arr[j - gap] > temp:
arr[j] = arr[j - gap]
j -= gap
arr[j] = temp
return arr
def hibbard_shell_sort(arr): n = len(arr) k = 0 while (1 << k) - 1 < n: k += 1 gaps = [1] for i in range(k): gaps.append((1 << (2 * i)) - 1) for gap in reversed(gaps): for i in range(gap, n): temp = arr[i] j = i while j >= gap and arr[j - gap] > temp: arr[j] = arr[j - gap] j -= gap arr[j] = temp
template <typename T> void hibbardShellSort(vector<T> &arr) { // Calculate the size of the array int n = arr.size(); // Calculate the number of levels in the tree int k = 1; // Calculate the number of elements in each level of the tree while ((1 << k) - 1 < n) { k++; } // Sort each level of the tree for (int gap = (1 << (k - 1)) - 1; gap > 0; gap = (gap >> 1) - 1) { // Sort each element in the level for (int i = gap; i < n; ++i) { // Store the current element in a temporary variable T temp = arr[i]; // Find the correct position for the element int j; for (j = i; j >= gap && arr[j - gap] > temp; j -= gap) { // Move the element to the correct position arr[j] = arr[j - gap]; } // Put the element in its correct position arr[j] = temp; } } }
def shell_sort(arr): n = len(arr) gap = n // 2 while gap > 0: for i in range(gap, n): temp = arr[i] j = i while j >= gap and arr[j - gap] > temp: arr[j] = arr[j - gap] j -= gap arr[j] = temp gap //= 2 def hibbard_shell_sort(arr): n = len(arr) k = 0 while (1 << k) - 1 < n: k += 1 gaps = [1] for i in range(k): gaps.append((1 << (2 * i)) - 1) for gap in reversed(gaps): for i in range(gap, n): temp = arr[i] j = i while j >= gap and arr[j - gap] > temp: arr[j] = arr[j - gap] j -= gap arr[j] = temp def knuth_shell_sort(arr): n = len(arr) k = 0 fib = 1 while fib < n: k += 1 fib = (k % 2 == 0) and (3 * fib + 1) or (3 * fib - 1) gaps = [(fib - 1) for i in range(k, 0, -1)] for gap in reversed(gaps): for i in range(gap, n): temp = arr[i] j = i while j >= gap and arr[j - gap] > temp: arr[j] = arr[j - gap] j -= gap arr[j] = temp def sedgewick_shell_sort(arr): n = len(arr) gap = 1 while gap < n / 3: gap = 3 * gap + 1 while gap > 0: for i in range(gap, n): temp = arr[i] j = i while j >= gap and arr[j - gap] > temp: arr[j] = arr[j - gap] j -= gap arr[j] = temp gap //= 3 class Person: def __init__(self, name, age, score): self.name = name self.age = age self.score = score def __lt__(self, other): return self.score < other.score def __le__(self, other): return self.score <= other.score def __eq__(self, other): return self.score == other.score and self.age == other.age and self.name == other.name def __ne__(self, other): return not self.__eq__(other) def __gt__(self, other): return self.score > other.score def __ge__(self, other): return self.score >= other.score def get_name(self): return self.name def get_age(self): return self.age def get_score(self): return self.score def test_shell_sort(): data = [9, 8, 3, 7, 5, 6, 4, 1] shell_sort(data) print(data) d_data = [9.9, 9.1, 3.3, 7.7, 5.5, 6.6, 4.4, 1.1] shell_sort(d_data) print(d_data) c_data = ['a', 'c', 'b', 'd', 'e'] shell_sort(c_data) print(c_data) p_data = [Person("Alice", 20, 90), Person("Bob", 18, 85), Person("Charlie", 22, 95)] shell_sort(p_data) for person in p_data: print(person.get_name(), person.get_age(), person.get_score()) def test_hibbard_shell_sort(): data = [9, 8, 3, 7, 5, 6, 4, 1] hibbard_shell_sort(data) print(data) d_data = [9.9, 9.1, 3.3, 7.7, 5.5, 6.6, 4.4, 1.1] hibbard_shell_sort(d_data) print(d_data) c_data = ['a', 'c', 'b', 'd', 'e'] hibbard_shell_sort(c_data) print(c_data) p_data = [Person("Alice", 20, 90), Person("Bob", 18, 85), Person("Charlie", 22, 95)] hibbard_shell_sort(p_data) for person in p_data: print(person.get_name(), person.get_age(), person.get_score()) def test_knuth_shell_sort(): data = [9, 8, 3, 7, 5, 6, 4, 1] knuth_shell_sort(data) print(data) d_data = [9.9, 9.1, 3.3, 7.7, 5.5, 6.6, 4.4, 1.1] knuth_shell_sort(d_data) print(d_data) c_data = ['a', 'c', 'b', 'd', 'e'] knuth_shell_sort(c_data) print(c_data) p_data = [Person("Alice", 20, 90), Person("Bob", 18, 85), Person("Charlie", 22, 95)] knuth_shell_sort(p_data) for person in p_data: print(person.get_name(), person.get_age(), person.get_score()) def test_sedgewick_shell_sort(): data = [9, 8, 3, 7, 5, 6, 4, 1] sedgewick_shell_sort(data) print(data) d_data = [9.9, 9.1, 3.3, 7.7, 5.5, 6.6, 4.4, 1.1] sedgewick_shell_sort(d_data) print(d_data) c_data = ['a', 'c', 'b', 'd', 'e'] sedgewick_shell_sort(c_data) print(c_data) p_data = [Person("Alice", 20, 90), Person("Bob", 18, 85), Person("Charlie", 22, 95)] sedgewick_shell_sort(p_data) for person in p_data: print(person.get_name(), person.get_age(), person.get_score()) if __name__ == "__main__": test_shell_sort() test_hibbard_shell_sort() test_knuth_shell_sort() test_sedgewick_shell_sort()
#include <iostream> #include <array> #include <algorithm> #include <vector> #include <string> using namespace std; class Person { public: Person(string name, int age, int score) { this->name = name; this->age = age; this->socre = score; } // Override the operator> for other function to use. bool operator>(const Person &other) const { // Compare the socre of two Person objects. return this->socre > other.socre; } // Override the operator< for other function to use. bool operator<(const Person &other) const { // Compare the socre of two Person objects. return this->socre < other.socre; } // Override the operator== for other function to use. bool operator==(const Person &other) const { // Compare the socre, age and name of two Person objects. return this->socre == other.socre && this->age == other.age && this->name == other.name; } // Override the operator!= for other function to use. bool operator!=(const Person &other) const { // Compare the socre, age and name of two Person objects. return this->socre != other.socre || this->age != other.age || this->name != other.name; } // Override the operator<= for other fnction to use. bool operator<=(const Person &other) const { // Compare the socre, age and name of two Person objects. return this->socre <= other.socre && this->age <= other.age && this->name <= other.name; } // Override the operator>= for other function to use. bool operator>=(const Person &other) const { // Compare the socre, age and name of two Person objects. return this->socre >= other.socre && this->age >= other.age && this->name >= other.name; } // Now there are some get parameters function for this calss: const string &getName() const { return this->name; } int getAge() const { return this->age; } int getScore() const { return this->socre; } private: string name; int age; int socre; }; template <typename T> void shellSort(vector<T> &arr) { // n is the size of the array int n = arr.size(); // gap is the difference between the current position and the gap position for (int gap = n / 2; gap > 0; gap /= 2) { // i is the current position for (int i = gap; i < n; ++i) { // temp is the current element T temp = arr[i]; // j is the gap position int j; // loop from i to gap and swap the elements if the gap position is greater than the current element for (j = i; j >= gap && arr[j - gap] > temp; j -= gap) { arr[j] = arr[j - gap]; } // swap the current element with the gap position arr[j] = temp; } } } void shellSortTestCase() { vector<int> data = {9, 8, 3, 7, 5, 6, 4, 1}; shellSort<int>(data); for (int i : data) { cout << i << " "; } cout << endl; vector<double> dData = {9.9, 9.1, 3.3, 7.7, 5.5, 6.6, 4.4, 1.1}; shellSort<double>(dData); for (double i : dData) { cout << i << " "; } cout << endl; vector<char> cData = {'a', 'c', 'b', 'd', 'e'}; shellSort<char>(cData); for (char i : cData) { cout << i << " "; } cout << endl; vector<Person> pData = {Person("Alice", 20, 90), Person("Bob", 18, 85), Person("Charlie", 22, 95)}; shellSort<Person>(pData); for (Person i : pData) { cout << i.getName() << " " << i.getAge() << " " << i.getScore() << endl; } cout << endl; } template <typename T> void hibbardShellSort(vector<T> &arr) { // Calculate the size of the array int n = arr.size(); // Calculate the number of levels in the tree int k = 1; // Calculate the number of elements in each level of the tree while ((1 << k) - 1 < n) { k++; } // Sort each level of the tree for (int gap = (1 << (k - 1)) - 1; gap > 0; gap = (gap >> 1) - 1) { // Sort each element in the level for (int i = gap; i < n; ++i) { // Store the current element in a temporary variable T temp = arr[i]; // Find the correct position for the element int j; for (j = i; j >= gap && arr[j - gap] > temp; j -= gap) { // Move the element to the correct position arr[j] = arr[j - gap]; } // Put the element in its correct position arr[j] = temp; } } } void hibbardShellSortTestCase() { vector<int> data = {9, 8, 3, 7, 5, 6, 4, 1}; hibbardShellSort<int>(data); for (int i : data) { cout << i << " "; } cout << endl; vector<double> dData = {9.9, 9.1, 3.3, 7.7, 5.5, 6.6, 4.4, 1.1}; hibbardShellSort<double>(dData); for (double i : dData) { cout << i << " "; } cout << endl; vector<char> cData = {'a', 'c', 'b', 'd', 'e'}; hibbardShellSort<char>(cData); for (char i : cData) { cout << i << " "; } cout << endl; vector<Person> pData = {Person("Alice", 20, 90), Person("Bob", 18, 85), Person("Charlie", 22, 95)}; hibbardShellSort<Person>(pData); for (Person i : pData) { cout << i.getName() << " " << i.getAge() << " " << i.getScore() << endl; } cout << endl; } template <typename T> void knuthShellSort(vector<T> &arr) { // find the length of the array int n = arr.size(); // initialize the gap int k = 0; // initialize the fibonacci number long long fib = 1; // calculate the fibonacci number while (fib < n) { k++; fib = (k % 2 == 0) ? (3 * fib + 1) : (3 * fib - 1); } // create a vector to store the gaps vector<int> gaps; // calculate the gaps for (int i = k; i >= 0; i--) { fib = (i % 2 == 0) ? (3 * fib + 1) : (3 * fib - 1); gaps.push_back(static_cast<int>(fib) - 1); } // sort the array using the gaps for (auto gap = gaps.rbegin(); gap != gaps.rend(); ++gap) { // sort the array within the gap for (int i = *gap; i < n; ++i) { T temp = arr[i]; int j; // find the correct position for (j = i; j >= *gap && arr[j - *gap] > temp; j -= *gap) { arr[j] = arr[j - *gap]; } arr[j] = temp; } } } void knuthShellSortTestCase() { vector<int> data = {9, 8, 3, 7, 5, 6, 4, 1}; knuthShellSort<int>(data); for (int i : data) { cout << i << " "; } cout << endl; vector<double> dData = {9.9, 9.1, 3.3, 7.7, 5.5, 6.6, 4.4, 1.1}; knuthShellSort<double>(dData); for (double i : dData) { cout << i << " "; } cout << endl; vector<char> cData = {'a', 'c', 'b', 'd', 'e'}; knuthShellSort<char>(cData); for (char i : cData) { cout << i << " "; } cout << endl; vector<Person> pData = {Person("Alice", 20, 90), Person("Bob", 18, 85), Person("Charlie", 22, 95)}; knuthShellSort<Person>(pData); for (Person i : pData) { cout << i.getName() << " " << i.getAge() << " " << i.getScore() << endl; } cout << endl; } template <typename T> void sedgewickShellSort(vector<T> &arr) { int n = arr.size(); int i = 0; while ((9 * (1 << (2 * i)) - 9 * (1 << i) + 1) < n) { i++; } vector<int> gaps; for (int j = 0; j < i; j++) { gaps.push_back(9 * (1 << (2 * j)) - 9 * (1 << j) + 1); } for (auto gap = gaps.rbegin(); gap != gaps.rend(); ++gap) { for (int i = *gap; i < n; ++i) { T temp = arr[i]; int j; for (j = i; j >= *gap && arr[j - *gap] > temp; j -= *gap) { arr[j] = arr[j - *gap]; } arr[j] = temp; } } } void sedgewickTestCase() { vector<int> data = {9, 8, 3, 7, 5, 6, 4, 1}; sedgewick<int>(data); for (int i : data) { cout << i << " "; } cout << endl; vector<double> dData = {9.9, 9.1, 3.3, 7.7, 5.5, 6.6, 4.4, 1.1}; sedgewick<double>(dData); for (double i : dData) { cout << i << " "; } cout << endl; vector<char> cData = {'a', 'c', 'b', 'd', 'e'}; sedgewick<char>(cData); for (char i : cData) { cout << i << " "; } cout << endl; vector<Person> pData = {Person("Alice", 20, 90), Person("Bob", 18, 85), Person("Charlie", 22, 95)}; sedgewick<Person>(pData); for (Person i : pData) { cout << i.getName() << " " << i.getAge() << " " << i.getScore() << endl; } cout << endl; } int main() { shellSortTestCase(); hibbardShellSortTestCase(); knuthShellSortTestCase(); sedgewickTestCase(); return 0; }
Copyright © 2003-2013 www.wpsshop.cn 版权所有,并保留所有权利。