Sorting algorithm four direct selection sort __ data structure and algorithm

1, directly select the concept of sorting:

Select the smallest element from the disordered area and put it directly into the end of the ordered area.

The direct selection sort and the direct insertion sort, all divide the data into ordered and unordered areas, the difference is that the direct insertion sort is to insert the first element of the unordered area directly into the ordered area to form a larger ordered region, and the direct selection order is the last of the smallest element from the disordered area to the ordered area. 2, direct selection of sorting characteristics:

Time complexity: O (n^2) (best time complexity: O (n^2) The worst time complexity O (n^2))

Complexity of Space: O (1)

Stability: Unstable

Note:

(1) After each trip of the select sort and bubble sort, there is an element in the final position. (leftmost or most right)

(2) Select the number of comparisons in the sorting process regardless of the initial state of the sequence, all the best and worst time complexity is O (n^2)

3. Implementation steps:

Set Array to arr[0...n-1]

1. Initialization array is unordered area arr[0...n-1]. Make I=0

2. Select a minimum element in the unordered area arr[0...n-1], swap it with Arr[i], and then arr[0...i] form an ordered area.

3.i++ and repeats the second step until the i==n-1, sorting is complete.

For example: The direct selection sort process for sequence {38,97,26,19,38*,15} is as follows:

4. Java Code Implementation

public void Selectsort (int[] arr) {
      int n = arr.length;
      for (int i = 0;i<n;i++) {
          int minindex = i;//Set the position of the smallest element for
          (int j = i+1;j<n;j++) {
              if (arr[j]<arr[ Minindex]) {
                   minindex = j;
              }
           }
           Place this element at the beginning of the unordered section
           int temp = arr[i];
           Arr[i] = Arr[minindex];
           Arr[minindex] = temp;
      }
}