Sorting algorithm - Selection Sort

The basic idea

Default unsorted first region a minimum first element, and then pick the smallest element in the element from the rear, with the switching element, until the cycle is complete.

Algorithm code

1  // simple selection sort 
2  void SelectSort ( int * ARR, int n-)
 . 3  {
 . 4      int I, J;
 . 5      int TEMP;
 . 6      int minIndex;
 . 7      for (I = 0 ; I <n-- 1 ; I ++) / / do i-times sorted, total n-1 times, since the n-th Run only a constant is the largest 
. 8      {
 . 9          minIndex = i;
 10          for (J = i + . 1 ; J <n; J ++ )
 . 11          {
 12 is              IF (arr [j] <arr [minIndex])
 13                  minIndex = j;
14          }
 15          if (minIndex! = I) // 后面有更小的元素
16          {
 17              temp = arr [i];
18              arr [i] = arr [minIndex];
19              arr [minIndex] = temp;
20          }
 21      }
 22 }

Analysis of Algorithms

I from the selected record in the minimum recording requires a relatively i -1 times.

Of I (I = 0 ~ n-2-) selected from ni times the minimum recording record requires a relatively ni-1.

N records for simple selection sort are necessary for the number of comparisons keyword amount to:

 

Number of movements recorded positive sequence is the minimum value 0, in reverse order of the maximum value of 3 (n-1). 

Sort select the best and the worst average time complexity of O (N2) .