(3) Sorting algorithm: insertion sort

Insertion sort: For every piece of data coming in from the outside of the queue, compare it with the ordered queue starting from the maximum value. After finding a suitable position, move the ordered queue and insert the new data into the corresponding position.

 

code and debugging results:

#include <iostream>

using namespace std;



template <class T>
void insert_sort(T list[],int n)
{
	T in, out,tmp;

	for (out = 1; out < n; out++) //out从下标1开始的,第0个已经提前出来放好了
	{
		in = out;
		tmp = list[out];
		while (in > 0 && list[in - 1] > tmp)
		{
			list[in] = list[in - 1];  //移动已序队列

			in--;
		}
		list[in] = tmp;

	}

}

int main()
{
	int arry[10] = {5,6,2,7,3,1,9,0,4,8};

	insert_sort<int>(arry,sizeof(arry)/sizeof(arry[0]));

	for (int i = 0; i < sizeof(arry) / sizeof(arry[0]); i++)
		cout << arry[i] << " ";

	cout << endl << endl << endl;

	return 0;
}

Time complexity of insertion sort:

    Number of comparisons: 1 + 2 + 3 ... + (N-2) + (N-1) = N^2/2-N/2

   Number of exchanges: 1 + 2 + 3 ... + (N-2) + (N-1) = N^2/2-N/2

  The total number of times is: N^2-N

   According to the Big O derivation rule, the final time complexity is O(N^2)