排序（ACM模式）冒泡选择插入快排

Posted 2021-10-15 久病成良医

排序算法

• 1. 冒泡
• 2. 选择
• 3. 插入
• 4. 快排

1. 冒泡

#include <iostream>
#include <vector>

using namespace std;

void print(vector<int>&nums)
{
	for (auto i : nums)
		cout << i << " ";
	cout << endl;
}

void bubblesort(vector<int>&nums, int n)
{
	for (int i = 0; i < n; i++)
	{
		for (int j = 0; j < n - 1 - i; j++)
		{
			if (nums[j] > nums[j + 1])
				swap(nums[j+1],nums[j]);
		}
	}
}

int main()
{
	int n;
	cin >> n;
	vector<int> nums;  //vector<int> nums(n);写成这样会出错
	int temp;
	for (int i = 0; i < n; i++)
	{
		cin >> temp;
		nums.push_back(temp);
	}
	bubblesort(nums, n);
	print(nums);
	return 0;
}

2. 选择

#include <iostream>
#include <vector>

using namespace std;

void print(vector<int>&nums)
{
	for (auto i : nums)
		cout << i << " ";
	cout << endl;
}

void selectsort(vector<int>&nums, int n)
{
	int minindex;
	for (int i = 0; i < n; i++)
	{
		minindex = i;
		for (int j = i + 1; j < n; j++)
		{
			if (nums[j] < nums[minindex])
			{
				minindex = j;
			}
		}
		swap(nums[i],nums[minindex]);
	}
}

int main()
{
	int n;
	cin >> n;
	vector<int>nums;
	int temp;
	for (int i = 0; i < n; i++)
	{
		cin >> temp;
		nums.push_back(temp);
	}
	selectsort(nums, n);
	print(nums);
	return 0;
}

3. 插入

#include <iostream>
#include <vector>

using namespace std;

void print(vector<int>&nums)
{
	for (auto i : nums)
		cout << i << " ";
	cout << endl;
}

void insertsort(vector<int>&nums, int n)
{                                                             //i = 2,要排3个数
	for (int i = 0; i < n; i++)  //i相当于需要排序的个数        // 5  6  3
	{                                                         //    3  6
		for (int j = i; j>0; j--)  //对i个数进行交换排序        // 3  5  6 
		{
			if (nums[j] < nums[j - 1])
				swap(nums[j],nums[j-1]);
		}
	}
}

int main()
{
	int n;
	cin >> n;
	vector<int>nums;
	int temp;
	for (int i = 0; i < n; i++)
	{
		cin >> temp;
		nums.push_back(temp);
	}
	insertsort(nums, n);
	print(nums);
	return 0;
}

4. 快排

#include <iostream>
#include <vector>

using namespace std;

void print(vector<int>&nums)
{
	for (auto i : nums)
		cout << i << " ";
	cout << endl;
}

void quicksort(vector<int>&nums, int first, int last)
{
	if (first >= last)  return;
	int left = first;
	int right = last;
	int index = nums[left];
	while (left < right&&nums[right] > index)
		right--;
	if (left < right&&nums[right] < index)
		nums[left] = nums[right];  //nums[left++] = nums[right];
	while (left < right&&nums[left] <= index)
		left++;
	if (left<right&&nums[left]>index)
		nums[right] = nums[left];  //nums[right--] = nums[left];
	nums[left] = index;
	quicksort(nums, first, left - 1);
	quicksort(nums, left + 1, last);
}

int main()
{
	int n;
	cin >> n;
	vector<int> nums;
	int temp;
	for (int i = 0; i < n; i++)
	{
		cin >> temp;
		nums.push_back(temp);
	}
	quicksort(nums, 0, n-1);
	print(nums);
	return 0;
}