64 lines
2.1 KiB
C#
64 lines
2.1 KiB
C#
using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Text;
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namespace NegativeBaseNumbers {
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class Program {
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const string DIGITS = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
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static string EncodeNegativeBase(long n, int b) {
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if (b < -62 || b > -1) {
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throw new ArgumentOutOfRangeException("b");
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}
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if (n == 0) {
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return "0";
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}
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StringBuilder output = new StringBuilder();
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long nn = n;
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while (nn != 0) {
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int rem = (int)(nn % b);
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nn /= b;
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if (rem < 0) {
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nn++;
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rem -= b;
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}
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output.Append(DIGITS[rem]);
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}
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return new string(output.ToString().Reverse().ToArray());
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}
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static long DecodeNegativeBase(string ns, int b) {
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if (b < -62 || b > -1) {
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throw new ArgumentOutOfRangeException("b");
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}
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if (ns == "0") {
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return 0;
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}
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long total = 0;
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long bb = 1;
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for (int i = ns.Length - 1; i >= 0; i--) {
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char c = ns[i];
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total += DIGITS.IndexOf(c) * bb;
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bb *= b;
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}
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return total;
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}
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static void Main(string[] args) {
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List<Tuple<long, int>> nbl = new List<Tuple<long, int>>() {
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new Tuple<long, int>(10,-2),
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new Tuple<long, int>(146,-3),
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new Tuple<long, int>(15,-10),
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new Tuple<long, int>(-34025238427,-62),
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};
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foreach (var p in nbl) {
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string ns = EncodeNegativeBase(p.Item1, p.Item2);
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Console.WriteLine("{0,12} encoded in base {1,-3} = {2}", p.Item1, p.Item2, ns);
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long n = DecodeNegativeBase(ns, p.Item2);
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Console.WriteLine("{0,12} decoded in base {1,-3} = {2}", ns, p.Item2, n);
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Console.WriteLine();
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}
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}
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}
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}
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