euler2025.go

package main

import (
	"fmt"
	"math"
)

func magnitude(v int64) int64 {
	if v == 0 {
		return 0
	}
	result := int64(10)
	for v > result {
		result *= 10
	}
	return result
}

func reconcatenate(a, b int64) int64 {
	return a*magnitude(b) + b
}

func sqrtInt(val int64) int64 {
	return int64(math.Sqrt(float64(val)))
}
func sqr(a int64) int64 {
	return a * a
}

func checkNumber(val int64) bool {
	if sqr(sqrtInt(val)) != val {
		return false
	}

	split := int64(10)
	for val > split {
		a := val / split
		b := val % split

		if reconcatenate(a, b) == val && val == (a+b)*(a+b) {
			fmt.Printf("(%d + %d)^2 = %d\n", a, b, val)
			return true
		}

		split *= 10
	}
	return false
}

func countAccepted(numDigits int64) int64 {
	result := int64(0)
	max := maxNumber(numDigits)
	maxSqrt := sqrtInt(max)
	for i := range maxSqrt {
		val := i * i
		if checkNumber(val) {
			println("accepted:", val)
			result += val
		}
		if i%100000000 == 0 {
			fmt.Printf("progress: %.6f%% \n", float64(i)/float64(maxSqrt)*100)
		}
	}
	return result
}

func maxNumber(numDigits int64) int64 {
	result := int64(1)
	for range numDigits {
		result *= 10
	}
	return result
}


func main() {
	println("total:", countAccepted(16))
}