add selection sort

Author: colynn

.gitignore

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+.vscode/

go.mod

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+module algorithm
+
+go 1.14
+
+require github.com/stretchr/testify v1.6.1

go.sum

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+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
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+github.com/stretchr/testify v1.6.1 h1:hDPOHmpOpP40lSULcqw7IrRb/u7w6RpDC9399XyoNd0=
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+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

selection_sort.go

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+package algorithm
+
+// SelectionSort ..
+// 算法步骤：
+// 首先在未排序序列中找到最小（大）元素，存放到排序序列的起始位置。
+// 再从剩余未排序元素中继续寻找最小（大）元素，然后放到已排序序列的末尾。
+// 重复第二步，直到所有元素均排序完毕。
+func SelectionSort(arr []int) []int {
+	length := len(arr)
+	for i := 0; i < length-1; i++ {
+		min := i
+		for j := i + 1; j < length; j++ {
+			if arr[min] > arr[j] {
+				min = j
+			}
+		}
+		arr[i], arr[min] = arr[min], arr[i]
+	}
+	return arr
+}

selection_sort_test.go

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+package algorithm
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestSelectionSort(t *testing.T) {
+	arr := []int{3, 2, 0, 5, 10, 1}
+	arrSort := SelectionSort(arr)
+	fmt.Printf("arr after sored: %v\n", arrSort)
+	assert.Equal(t, 10, arrSort[5])
+	assert.Equal(t, 5, arrSort[4])
+}