选择排序 selection Sort

概述

按指定的规则选出来某个元素，再依规定交换位置.可以不断缩小范围将最小值放在前方。

图解过程

// Find the minimum element in arr[0…4]
// and place it at beginning
11 25 12 22 64

// Find the minimum element in arr[1…4]
// and place it at beginning of arr[1…4]
11 12 25 22 64

// Find the minimum element in arr[2…4]
// and place it at beginning of arr[2…4]
11 12 22 25 64

// Find the minimum element in arr[3…4]
// and place it at beginning of arr[3…4]
11 12 22 25 64

造轮子

public void sort(int arr[]) 
   { 
       int n = arr.length; 
 
       // One by one move boundary of unsorted subarray 
       for (int i = 0; i < n-1; i++) 
       { 
           // Find the minimum element in unsorted array 
           int min_idx = i; 
           for (int j = i+1; j < n; j++) 
               if (arr[j] < arr[min_idx]) 
                   min_idx = j; 
 
           // Swap the found minimum element with the first 
           // element 
           int temp = arr[min_idx]; 
           arr[min_idx] = arr[i]; 
           arr[i] = temp; 
       } 
   }