Selection sort in Go

Author: hansrajdas

Level-2/bubble-sort.go

@@ -1,5 +1,5 @@
 /*
-Date: 2018-09-08
+Date: 2023-12-28
 
 Description:
 Implement bubble sort.

Level-2/selection-sort.go

@@ -0,0 +1,56 @@
+/*
+Date: 2023-12-29
+
+Description:
+Implement selection sort.
+
+Approach:
+Finds index of minimum (when sorting in ascending) element from the remaining
+array and swap it with element at the end of sorted sub-array.
+While sorting in ascending order minimum element reaches at first place after
+first iteration of outer loop.
+
+Complexity:
+O(n^2)
+*/
+
+package main
+
+import (
+	"fmt"
+	"reflect"
+)
+
+func selectionSort(nums []int) {
+	for i := 0; i < len(nums); i++ {
+		minIdx := i
+		for j := i + 1; j < len(nums); j++ {
+			// For sorting in descending order, find maxIdx.
+			if nums[j] < nums[minIdx] {
+				minIdx = j
+			}
+		}
+		nums[minIdx], nums[i] = nums[i], nums[minIdx]
+	}
+}
+
+func main() {
+	testCases := []struct {
+		input, expected []int
+	}{
+		{input: []int{5, 4, 3, 2, 1, 10, 28, 7, 6}, expected: []int{1, 2, 3, 4, 5, 6, 7, 10, 28}},
+		{input: []int{3, 4, 5, 2, 1}, expected: []int{1, 2, 3, 4, 5}},
+		{input: []int{3, 4, 5, 2, 1, 6}, expected: []int{1, 2, 3, 4, 5, 6}},
+		{input: []int{}, expected: []int{}},
+		{input: []int{1}, expected: []int{1}},
+		{input: []int{2, 1}, expected: []int{1, 2}},
+	}
+	for idx, tc := range testCases {
+		inputCopy := make([]int, len(tc.input))
+		copy(inputCopy, tc.input)
+		selectionSort(inputCopy)
+		if !reflect.DeepEqual(inputCopy, tc.expected) {
+			fmt.Printf("\nTC %d failed. Expected %v, got %v", idx, tc.expected, inputCopy)
+		}
+	}
+}

Level-2/selection_sort.py

@@ -1,19 +1,20 @@
 #!/usr/bin/python
 
-# Date: 2018-09-08
-#
-# Description:
-# Implement selection sort.
-#
-# Approach:
-# Finds index of minimum(when sorting in ascending) element from the remaining
-# array and swap it with element at the end of sorted sub-array.
-# While sorting in ascending order minimum element reaches at first place after
-# first iteration of outer loop.
-#
-# Complexity:
-# O(n^2)
+"""
+Date: 2018-09-08
 
+Description:
+Implement selection sort.
+
+Approach:
+Finds index of minimum(when sorting in ascending) element from the remaining
+array and swap it with element at the end of sorted sub-array.
+While sorting in ascending order minimum element reaches at first place after
+first iteration of outer loop.
+
+Complexity:
+O(n^2)
+"""
 
 def selection_sort_ascending(A):
     for i in range(len(A)):

README.md

@@ -3,7 +3,8 @@ All programs are categorized in level 1 to 4(1 being easiest)
 ## Sorting
 - [Bubble sort (Python)](Level-2/bubble_sort.py): Implement bubble sort in Python | O(n^2) | Level 2.
 - [Bubble sort (Go)](Level-2/bubble-sort.go): Implement bubble sort in Golang | O(n^2) | Level 2.
-- [Selection sort](Level-2/selection_sort.py): Implement selection sort in python | O(n^2) | Level 2.
+- [Selection sort (Python)](Level-2/selection_sort.py): Implement selection sort in Python | O(n^2) | Level 2.
+- [Selection sort (Go)](Level-2/selection-sort.go): Implement selection sort in Golang | O(n^2) | Level 2.
 - [Selection sort](Level-2/selection_sort.c): Implement selection sort in C| O(n^2) | Level 2.
 - [Insertion sort](Level-2/insertion_sort.py): Implement insertion sort | O(n^2) | Level 2.
 - [Heap sort using max heap](Level-3/heap_sort_using_max_heap.c): Build a max heap and sort array in ascending order | Level 3.