feat: saturday

pkg/two_sum/main.go

@@ -0,0 +1,49 @@
+package two_sum
+
+import (
+	"slices"
+)
+
+type Index struct {
+	Index int
+	Value int
+}
+
+func ByValue(a, b Index) int {
+	return a.Value - b.Value
+}
+
+func ToIndices(list []int) []Index {
+	result := []Index{}
+
+	for index, value := range list {
+		result = append(result, Index{index, value})
+	}
+
+	slices.SortFunc(result, ByValue)
+	return result
+}
+
+// https://leetcode.com/problems/two-sum/description/
+
+func TwoSum(nums []int, target int) []int {
+	numbers := ToIndices(nums)
+	lower, upper := 0, len(numbers)-1
+
+	for lower < upper {
+		current_sum := numbers[lower].Value + numbers[upper].Value
+
+		if current_sum < target {
+			lower++
+		} else if current_sum > target {
+			upper--
+		} else {
+			return []int{
+				numbers[lower].Index,
+				numbers[upper].Index,
+			}
+		}
+	}
+
+	return nil
+}

pkg/two_sum/main_test.go

@@ -0,0 +1,14 @@
+package two_sum_test
+
+import (
+	"testing"
+
+	"git.maximhutz.com/practice/pkg/two_sum"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestTwoSum(t *testing.T) {
+	assert.Equal(t, two_sum.TwoSum([]int{2, 7, 11, 15}, 9), []int{0, 1})
+	assert.Equal(t, two_sum.TwoSum([]int{3, 2, 4}, 6), []int{1, 2})
+	assert.Equal(t, two_sum.TwoSum([]int{3, 3}, 6), []int{0, 1})
+}