1.冒泡排序

1.冒泡：
谁大谁上，每一轮都把最大的顶到天花板
效率太低 $O(n^2)$

可以设定一个flag来进行剪枝

#include<iostream>
#include<vector>

using namespace std;

void BubbleSort1(vector<int>& arr, int n) {
	int i, j, temp;
	bool swapped = false;
	for (i = 0; i < n - 1; i++)
	{
		swapped = false;
		for (j = 0; j < n - i - 1; j++)
		{
			if (arr[j] > arr[j + 1])
			{
				temp = arr[j];
				arr[j] = arr[j + 1];
				arr[j + 1] = temp;
				swapped = true;
			}
		}
		if (swapped == false)//剪枝操作
		{
			break;
		}
	}
}

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

int main(void)
{
	int n, i;
	cout << "Enter the number of elements: ";
	cin >> n;
	vector<int>arr(n);
	cout << "Enter the elements: ";
	for (i = 0; i < n; i++)
	{
		cin >> arr[i];
	}
	BubbleSort(arr, n);
	cout << "Sorted array: ";
	for (i = 0; i < n; i++)
	{
		cout << arr[i] << " ";
	}
	return 0;
}