Find pairs that equal target

pairs.go

package main

//Given a list of numbers and a number k, return whether any two numbers from the list add up to k.
//For example, given [10, 15, 3, 7] and k of 17, return true since 10 + 7 is 17.

import (
	"fmt"
	"math/rand"
)

func pairsFill(size int) []int {
	slice := make([]int, 0, size)
	for i := 0; i < size; i++ {
		slice = append(slice, int(rand.Float32()*10))
	}
	return slice
}

func hasPairForSum(nums []int, k int) bool {
	seen := make(map[int]bool)
	for _, n := range nums {
		if _, present := seen[k-n]; present {
			return true
		}
		seen[n] = true
	}
	return false
}

func main() {
	var (
		nums []int
		k    int
	)

	nums, k = pairsFill(6), 10
	fmt.Println(nums, k, hasPairForSum(nums, k))

	nums, k = pairsFill(6), 7
	fmt.Println(nums, k, hasPairForSum(nums, k))

	nums, k = pairsFill(6), 7
	fmt.Println(nums, k, hasPairForSum(nums, k))

	nums, k = pairsFill(1000000), 7
	fmt.Println(hasPairForSum(nums, k))
}