minhphong306/find_not_duplicate_number_sol4.go

## find_not_duplicate_number_sol4.go
func solution4(arr []int) int {
	var sumSingle, sumAll int
	mapCheck := make(map[int]bool)
	for _, item := range arr {
		if _, ok := mapCheck[item]; !ok {
			sumSingle += item
			mapCheck[item] = true
		}

		sumAll += item
	}

	return sumSingle*2 - sumAll
}
	func solution4(arr []int) int {
	var sumSingle, sumAll int
	mapCheck := make(map[int]bool)
	for _, item := range arr {
	if _, ok := mapCheck[item]; !ok {
	sumSingle += item
	mapCheck[item] = true
	}

	sumAll += item
	}

	return sumSingle*2 - sumAll
	}