sha256sentence.go

package main

import (
	"crypto/sha256"
	"encoding/hex"
	"fmt"
	"strings"
)

const msg = "The SHA256 for this sentence begins with: "

var counter = 0

func toString(arr []string, s2i map[string]string) string {
	b := strings.Builder{}
	for _, v := range arr {
		fmt.Fprint(&b, s2i[v])
	}

	return b.String()
}

func testShasum(arr []string, s2i map[string]string) string {
	counter++
	fullMsg := msg + strings.Join(arr[:6], ", ") + " and " + arr[6] + "."
	sum := sha256.Sum256([]byte(fullMsg))
	hexSum := hex.EncodeToString(sum[:])

	//fmt.Println(counter, fullMsg)

	if hexSum[:7] == toString(arr, s2i) {
		return fullMsg
	}

	return ""
}

func test(choices []string, s2i map[string]string, toTest []string, idx int) string {
	if idx == 7 {
		return testShasum(toTest, s2i)
	}

	for _, v := range choices {
		toTest[idx] = v
		result := test(choices, s2i, toTest, idx+1)
		if len(result) > 0 {
			return result
		}
	}

	return ""
}

func main() {
	k := []string{"one", "two", "three", "four", "five", "six", "seven", "eight", "nine", "a", "b", "c", "d", "e", "f"}
	m := map[string]string{
		"one":   "1",
		"two":   "2",
		"three": "3",
		"four":  "4",
		"five":  "5",
		"six":   "6",
		"seven": "7",
		"eight": "8",
		"nine":  "9",
		"a":     "a",
		"b":     "b",
		"c":     "c",
		"d":     "d",
		"e":     "e",
		"f":     "f",
	}

	fmt.Println(test(k, m, make([]string, 7), 0))
}