// challenge 305 Easy Permutation Base
// https://w...content-available-to-author-only...t.com/r/dailyprogrammer/comments/5xu7sz/20170306_challenge_305_easy_permutation_base/

//package challenge._305_easy

import java.math.BigInteger

fun toBinary(dec: String): String {
    var sb = StringBuilder()
    var v: BigInteger = BigInteger(dec)
    var n: BigInteger = BigInteger.valueOf(1)
    var bits: Int = 1
    val two: BigInteger = BigInteger.valueOf(2)
    while (true) {
        val nextN = n.multiply(two)
        if (v.compareTo(nextN) >= 0) {
            v = v.minus(nextN)
            n = nextN
            bits++
        } else {
            break
        }
    }
    while (bits > 0) {
        val rem = v.remainder(two)
        sb.append(rem.toString())
        v = v.divide(two)
        bits--
    }
    sb = sb.reverse()
    println("$dec -> ${sb.toString()}")
    return sb.toString()
}

fun toDecimal(bin: String): String {
    var v = BigInteger.ZERO
    var two = BigInteger.valueOf(2)
    for (i in 0..bin.length-1) {
        v = v.multiply(two) + BigInteger(bin[i].toString())
    }
    var offset = BigInteger.ZERO
    var n = BigInteger.valueOf(1)
    var bits = bin.length-1
    for (i in 1..bits) {
        n = n.multiply(two)
        offset = offset.add(n)
    }
    v = v.add(offset)
    println("$bin -> $v")
    return v.toString()
}

fun main(args: Array<String>) {
    toDecimal(toBinary("54"))
    toBinary(toDecimal("111000111"))
    toDecimal(toBinary("234234234"))
    toDecimal(toBinary("234234234234234"))
    toDecimal(toBinary("234234234234234234234234"))
    toBinary(toDecimal("000111000111111000111111000111111000111"))
    toBinary(toDecimal("11111111000111000111111000111111000111111000111"))
}