gistfile1.go

package main

import (
  "github.com/fighterlyt/permutation"
)

func formSolution(arr []int) []Solution {
	solution := []Solution{}
	for i := 0; i < len(arr); i += 2 {
		solution = append(solution, Solution{arr[i], arr[i+1]})
	}
	return solution
}

func naive(rules []Rule) []Solution {
	perm, _ := NewPerm(options, nil)

	nextPerm, _ := perm.Next()
	currentSolution := formSolution(nextPerm.([]int))
	for !isCorrect(currentSolution) && perm.Left() > 0 {
		nextPerm, _ = perm.Next()
		currentSolution = formSolution(nextPerm.([]int))
	}

	return currentSolution
}

gistfile2.go

package main

import (
	"fmt"
)

type Rule struct {
	op     string
	result int
}

type Solution struct {
	left  int
	right int
}

var (
	rules   []Rule
	options []int
)

func contains(s []int, e int) bool {
	for _, a := range s {
		if a == e {
			return true
		}
	}
	return false
}

func isSolution(sol Solution, rule Rule) bool {
	if applyOp(rule.op, sol) == rule.result {
		return true
	}
	return false
}

func applyOp(op string, sol Solution) int {
	switch op {
	case "+":
		return sol.left + sol.right
	case "-":
		return sol.left - sol.right
	}
	return 0
}

func isCorrect(solution []Solution) bool {
	index := 0
	for index < len(rules) {
		if index > 2 {
			fmt.Println(solution)
		}
		if !isSolution(solution[index], rules[index]) {
			return false
		}
		index += 1
	}
	return true
}

func initVars() {
	rules = []Rule{
		{"-", 1},
		{"+", 9},
		{"-", 2},
		{"+", 7},
	}
	options = []int{1, 2, 3, 4, 5, 6, 7, 8}
}

func main() {
	initVars()
	var naiveSolution []Solution = naive(rules)
	fmt.Println("The rules are: ", rules)
	fmt.Println("The naive method returns: ", naiveSolution)
}