Two Sum

Go to the battlefield

Instructions#

Given an array of integers nums and an integer target, return indices of the two numbers such that they add up to target.

You may assume that each input would have exactly one solution, and you may not use the same element twice.

func TwoSum(nums []int, target int) []int {

}

Test Cases#

func TestTwoSum(t *testing.T) {
	if ok := TwoSum([]int{2,7,11,15}, 9); ok[0] != 0 || ok[1] != 1 {
		t.Error("Expected [0,1], got ", ok)
	}

	if ok := TwoSum([]int{3,2,4}, 6); ok[0] != 1 || ok[1] != 2 {
		t.Error("Expected [1,2], got ", ok)
	}

	if ok := TwoSum([]int{3,3}, 6); ok[0] != 0 || ok[1] != 1 {
		t.Error("Expected [0,1], got ", ok)
	}
}

Solution#

func TwoSum(nums []int, target int) []int {
	m := make(map[int]int)

	for i := 0; i < len(nums); i++ {
		v := target - nums[i]

		if _, ok := m[v]; ok {
			return []int{m[v], i}
		}

		m[nums[i]] = i
	}

	return nil
}

Discourse#

See js/0001-two-sum#discourse to get details.