minmax

Minimum | Maximum

Goal: Find the minimum|maximum object in an unsorted array.

Maximum or minimum

We have an array of generic objects and we iterate over all the objects keeping track of the minimum/maximum element so far.

An example

Let's say the we want to find the maximum value in the unsorted list [ 8, 3, 9, 4, 6 ].

Pick the first number, 8, and store it as the maximum element so far.

Pick the next number from the list, 3, and compare it to the current maximum. 3 is less than 8 so the maximum 8 does not change.

Pick the next number from the list, 9, and compare it to the current maximum. 9 is greater than 8 so we store 9 as the maximum.

Repeat this process until the all elements in the list have been processed.

The code

func Minimum(inputArray []int) int {
	if len(inputArray) == 0 {
		panic("Array must have at-least one element")
	}

	min := inputArray[0]

	for _, value := range inputArray {
		if value < min {
			min = value
		}
	}
	
	return min
}


func Maximum(inputArray []int) int {
	if len(inputArray) == 0 {
		panic("Array must have at-least one element")
	}

	max := inputArray[0]

	for _, value := range inputArray {
		if value > max {
			max = value
		}
	}
	
	return max
}

numbers := []int{11, 59, 3, 2, 53, 17, 31, 7, 19, 67, 47, 13, 37, 61, 29, 43, 5, 41, 23}
minmax.Minimum(array)   // This will return 2
minmax.Maximum(array)   // This will return 67

By picking elements in pairs and comparing their maximum and minimum with the running minimum and maximum we reduce the number of comparisons to 3 for every 2 elements.

Performance

These algorithms run at O(n). Each object in the array is compared with the running minimum/maximum so the time it takes is proportional to the array length.

Written by brotherpowers