selection_sort.go

package main

import (
	"slices"
)

func main() {
}

func find_smallest(arr []int) int {
	smallest_index := 0

	for idx, value := range arr {
		if value < arr[smallest_index] {
			smallest_index = idx
		}
	}
	return smallest_index
}

func selection_sort(arr []int) []int {
	sorted_arr := []int{}
	for len(arr) > 0 {
		smallest_index := find_smallest(arr)
		sorted_arr = append(sorted_arr, arr[smallest_index])
		arr = slices.Delete(arr, smallest_index, smallest_index+1)
	}
	return sorted_arr
}

selection_sort_test.go

package main

import (
	"reflect"
	"testing"
)

func TestFindSmallest(t *testing.T) {
	tests := []struct {
		name     string
		input    []int
		expected int
	}{
		{"Empty array", []int{}, 0},
		{"Single element", []int{1}, 0},
		{"Smallest at beginning", []int{1, 2, 3, 4}, 0},
		{"Smallest in middle", []int{4, 3, 1, 5}, 2},
		{"Smallest at end", []int{5, 4, 3, 1}, 3},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			if got := find_smallest(tt.input); got != tt.expected {
				t.Errorf("find_smallest() = %v, want %v", got, tt.expected)
			}
		})
	}
}

func TestSelectionSort(t *testing.T) {
	tests := []struct {
		name     string
		input    []int
		expected []int
	}{
		{"Empty array", []int{}, []int{}},
		{"Single element", []int{1}, []int{1}},
		{"Already sorted", []int{1, 2, 3, 4}, []int{1, 2, 3, 4}},
		{"Reverse sorted", []int{4, 3, 2, 1}, []int{1, 2, 3, 4}},
		{"Random order", []int{3, 1, 4, 2}, []int{1, 2, 3, 4}},
		{"Duplicate elements", []int{3, 1, 3, 2}, []int{1, 2, 3, 3}},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			// Create a copy of input to avoid modifying the original
			input := make([]int, len(tt.input))
			copy(input, tt.input)

			if got := selection_sort(input); !reflect.DeepEqual(got, tt.expected) {
				t.Errorf("selection_sort() = %v, want %v", got, tt.expected)
			}
		})
	}
}