package main

import "fmt"

func InterpolationSearch(array []int, key int) int {

	min, max := array[0], array[len(array)-1]

	low, high := 0, len(array)-1

	for {
		if key < min {
			return low
		}

		if key > max {
			return high + 1
		}

		// make a guess of the location
		var guess int
		if high == low {
			guess = high
		} else {
			size := high - low
			offset := int(float64(size-1) * (float64(key-min) / float64(max-min)))
			guess = low + offset
		}

		// maybe we found it?
		if array[guess] == key {
			// scan backwards for start of value range
			for guess > 0 && array[guess-1] == key {
				guess--
			}
			return guess
		}

		// if we guessed to high, guess lower or vice versa
		if array[guess] > key {
			high = guess - 1
			max = array[high]
		} else {
			low = guess + 1
			min = array[low]
		}
	}
}

func main() {
	searchValue := 0

	arr := []int{1, 5, 100, 0, -100, 15, 4, 102, 30, 1000}
	fmt.Println(arr)

	var index = InterpolationSearch(arr, searchValue)

	if index < 0 {
		fmt.Println("Not found")
		return
	} else {
		fmt.Println("Found at position: ", index)
		return
	}
}