func MissingInUnsorted(arr []int, lower, upper int) int {
	upperSum := upper * (upper + 1) / 2
	lowerSum := lower * (lower - 1) / 2

	sum := 0
	for _, v := range arr {
		sum += v
	}

	return (upperSum - lowerSum) - sum
}
// MissingInUnsorted finds the missing number from an unsorted array
MissingInUnsorted finds the missing number from an unsorted array
// MissingInUnsorted finds the missing number from an unsorted array
func MissingInUnsorted(arr []int, lower, upper int) int {
	upperSum := upper * (upper + 1) / 2
	lowerSum := lower * (lower - 1) / 2
	sum := 0
	for _, v := range arr {
		sum += v
	}
	return (upperSum - lowerSum) - sum
}
func MissingInUnsorted ( arr [ ] int , lower , upper int ) int { upperSum := upper * ( upper + 1 ) / 2 lowerSum := lower * ( lower - 1 ) / 2 sum := 0 for _ , v := range arr { sum += v } return ( upperSum - lowerSum ) - sum }
MissingInUnsorted finds the missing number from an unsorted array
MissingInUnsorted finds the missing number from an unsorted array