选择排序

Author: FantasyLWX

README.md

@@ -107,11 +107,13 @@
 
 - [插入排序][insertion-sort]
 - [希尔排序][shell-sort]
+- [选择排序][selection-sort]
 - [冒泡排序][bubble-sort]
 - [快速排序][quick-sort]
 
 [insertion-sort]: ./src/com/fantasy/algorithm/sort/InsertionSort.java
-[shell-sort]: ./src/com/fantasy/algorithm/sort/InsertionSort.java
+[shell-sort]: ./src/com/fantasy/algorithm/sort/ShellSort.java
+[selection-sort]: ./src/com/fantasy/algorithm/sort/SelectionSort.java
 [bubble-sort]: ./src/com/fantasy/algorithm/sort/BubbleSort.java
 [quick-sort]: ./src/com/fantasy/algorithm/sort/QuickSort.java
 

src/com/fantasy/algorithm/sort/SelectionSort.java

@@ -0,0 +1,51 @@
+package com.fantasy.algorithm.sort;
+
+import java.util.Arrays;
+
+/**
+ * 选择排序，稳定算法</br>
+ * </br>
+ * 选择排序每次会从未排序区间中找到最小的元素，将其放到已排序区间的末尾。</br>
+ * </br>
+ * 在最佳情况下，时间复杂度为 O(n^2)</br>
+ * </br>
+ * 在最差情况下，时间复杂度为 O(n^2)</br>
+ * </br>
+ * 在平均情况下，时间复杂度为 O(n^2)</br>
+ * </br>
+ * 空间复杂度为 O(1)
+ *
+ * <pre>
+ *     author  : Fantasy
+ *     version : 1.0, 2020-09-02
+ *     since   : 1.0, 2020-09-02
+ * </pre>
+ */
+public class SelectionSort {
+
+    public static void main(String[] args) {
+        int[] arr = new int[] { 4, 5, 6, 1, 3, 2 };
+        System.out.println("before : " + Arrays.toString(arr));
+        selectionSort(arr);
+        System.out.println("after : " + Arrays.toString(arr));
+    }
+
+    public static void selectionSort(int[] arr) {
+        int length = arr.length;
+        int indexMin;
+        for (int i = 0; i < length - 1; i++) {
+            indexMin = i;
+            for (int j = i + 1; j < length; j++) {
+                if (arr[j] < arr[indexMin]) {
+                    indexMin = j;
+                }
+            }
+            if (indexMin != i) {
+                int temp = arr[indexMin];
+                arr[indexMin] = arr[i];
+                arr[i] = temp;
+            }
+        }
+    }
+
+}