Sort - choose to sort

First, the algorithm thought

Maximum selection table L (small) elements, switching elements and the final position. It comprises the following steps:

1. For table L = (a1, az, a3 ,. ..., ai ..., an.), The order of traversal, the maximum element selected location, the last position of the switching element;
2. For the remainder of the child table except the last element composed of repeating (1), until the remaining part of the sub-table is composed of a length equal to the.

---

Second, the algorithm process

---

Third, to achieve

void SelectSort(int R[],int n)
{
	int i,j;
	int temp;
	int max_index;
	for(i=0;i<n;i++)
	{
		max_index=-1;
		for(j=0;j<n-i;j++)
		{
			if(R[j]>max_index)
				max_index=j;
		}
		if(max_index>=0)
		{
			j--;
			temp=R[max_index];
			R[max_index]=R[j];
			R[j]=temp;
		}
	}
}

---

Fourth, the algorithm performance analysis

(1) Time Complexity Analysis

Execution times of two cycles and the initial sequence does not matter, n times the outer loop, the inner loop is executed n-1 times, the comparison operation of the innermost loop as a key operation, which is performed n times (N- 1) / 2, so the average time complexity, worst case time complexity, are the best time complexity O (n ^ 2)

Complexity (2) Spatial Analysis

Space complexity is O (1)

(3) Stability

It can be seen from the statement if (R [j]> max_index), the algorithm will always encounter the maximum value added to the first sorted sequence (if they are the same value will be skipped), then the algorithm It is unstable. (If> into> =, the algorithm is stable, but this will increase the number of executions max_index = j)