From dc5970773c84b575d4a81115c7c8d79ef3572a1d Mon Sep 17 00:00:00 2001
From: hujanais <teikmenglee@yahoo.com>
Date: Sun, 15 Jan 2023 15:58:56 +0000
Subject: [PATCH] day25

---
 data/day25.txt     | 130 +++++++++++++++++++++++++++++++++++++++++++++
 data/day25test.txt |  13 +++++
 day25.js           | 130 +++++++++++++++++++++++++++++++++++++++++++++
 index.js           |   7 ++-
 4 files changed, 278 insertions(+), 2 deletions(-)
 create mode 100644 data/day25.txt
 create mode 100644 data/day25test.txt
 create mode 100644 day25.js

diff --git a/data/day25.txt b/data/day25.txt
new file mode 100644
index 0000000..f41b79a
--- /dev/null
+++ b/data/day25.txt
@@ -0,0 +1,130 @@
+110=11=10-=202=2-10
+200
+110120221-1021=0-
+10=1
+2=2-0=0
+2-2=
+1=2==
+10=2==0=
+2==1=200==-010=
+11=00
+1-=2
+1212
+2=-
+211-=02-2
+112
+1===-1=21
+1=212-0=12
+1=0=1
+2---0-=1=00
+1011=112--1-=
+1--02-1-
+21=21
+221
+1-2=-1=11----1=-=-
+212001101=
+211=2=02102-11-0
+1-210
+201-00
+2=0==000
+11011=1=-21=
+1=11=
+1==222=11
+100
+1==
+120-
+2=1=0
+1-101-2121----2
+1020--=2
+2=0==0-110
+2-=0-=-1==
+22=201-21020=20-1
+1-1220----=210-1=
+210=01
+20=0==2220=22=-022
+11=102
+1-1-=01-10---
+1=1
+1=2=1-122-0-=01020
+11=12
+2-
+1=2==1-=
+1221=211101-=010
+11=21-2--122-2
+11--1-
+1=0-2
+10=11=0
+1-2=02-2--0-
+2==-20--11-1
+1=1021=220112-=
+1--=1=202-022000
+1-=02--=-1=-12--
+11--00==0
+1=1022-1=-2
+1=11-22-
+1011=
+2=
+2-2-0-2-2=-
+12002=1=-110
+2
+11=1=2-1-0=
+2022201-100-2=02=2
+1111=0101210
+2001100-00=2-
+2=2202=0==20
+1=0
+1=1=0022-02-111-2-2
+21==10
+221==11=1-2-=221=2
+20=0-02=-01=-1101
+2====2-0=-==2
+1===0110=-
+2-20-101-01
+101-021=1112102
+2=-=1-=2=0101--
+1=20211=
+1=202=-=---1121=
+1==0200-=
+2=1=022=21--122=02
+1-1010-=-0222=1==1-2
+112=2=001-
+2121-=00=110=
+1--01-202
+1-==
+1-0011-
+1-001===0
+1=20-110-
+12010--==2-11-1=12
+1--0-1
+2=1-0=2=1-20
+111=11
+2-==--1=1201
+1=-
+100-22-0=-10021
+100==1-02111111=
+12---1==
+101==1
+202111-1120122=2
+2--
+212-
+1===02-1-=102-00
+111-10-=-0-==
+1-002101=0=
+220=1-01-=201-0
+1-2--112=01
+1-00
+11==10212=1
+1=10-==--
+2110020002
+1-==-==1--002
+2=011=-1=2=10===
+1=21101=20=2-
+21=02-00=21-02=
+10=0
+1--221120=2-0=-001
+111-0=-2010100=2
+11==1-11-011-1-
+2=220=1=
+11-0121==2=2=0-20
+1-001-1-02=-1=100
+1=11-210-02
\ No newline at end of file
diff --git a/data/day25test.txt b/data/day25test.txt
new file mode 100644
index 0000000..237ef0c
--- /dev/null
+++ b/data/day25test.txt
@@ -0,0 +1,13 @@
+1=-0-2
+12111
+2=0=
+21
+2=01
+111
+20012
+112
+1=-1=
+1-12
+12
+1=
+122
\ No newline at end of file
diff --git a/day25.js b/day25.js
new file mode 100644
index 0000000..bd45c90
--- /dev/null
+++ b/day25.js
@@ -0,0 +1,130 @@
+const { assert } = require('console');
+const fs = require('fs');
+
+const smallTest = [
+  [1, '1'],
+  [2, '2'],
+  [3, '1='],
+  [4, '1-'],
+  [5, '10'],
+  [6, '11'],
+  [7, '12'],
+  [8, '2='],
+  [9, '2-'],
+  [10, '20'],
+  [15, '1=0'],
+  [20, '1-0'],
+  [2022, '1=11-2'],
+  [12345, '1-0---0'],
+  [314159265, '1121-1110-1=0'],
+  [1747, '1=-0-2'],
+  [906, '12111'],
+  [198, '2=0='],
+  [11, '21'],
+  [201, '2=01'],
+  [31, '111'],
+  [1257, '20012'],
+  [32, '112'],
+  [353, '1=-1='],
+  [107, '1-12'],
+  [7, '12'],
+  [3, '1='],
+  [37, '122'],
+];
+
+day25a = () => {
+  // const filename = './data/day25test.txt';  // 4890 => 2=-1=0
+  const filename = './data/day25.txt';  // 33658310202841 2--1=0=-210-1=00=-=1
+  let arr = fs.readFileSync(filename, { encoding: 'utf8', flag: 'r' }).split('\n');
+
+  // test decode
+  for ([decimal, snafu] of smallTest) {
+    assert(decode(snafu) === decimal);
+  }
+
+  // test encode
+  for ([decimal, snafu] of smallTest) {
+    assert(encode(decimal) === snafu);
+  }
+
+  let snafuDecimal = 0;
+  for (let snafu of arr) {
+    snafuDecimal += decode(snafu);
+  }
+
+  let answer = encode(snafuDecimal);
+
+  console.log('day25a = ', snafuDecimal, answer);
+};
+
+day25b = () => {
+
+}
+
+const decode = (snafuStr) => {
+  const snafu = snafuStr.split('');
+  let power = snafu.length - 1;
+  let result = 0;
+  while (snafu.length > 0) {
+    const item = snafu.shift();
+    switch (item) {
+      case '-':
+        result -= 1 * Math.pow(5, power);
+        break;
+      case '=':
+        result -= 2 * Math.pow(5, power);
+        break;
+      default:
+        result += +item * Math.pow(5, power);
+        break;
+    }
+    power -= 1;
+  }
+
+  return result;
+};
+
+const encode = (decimalStr) => {
+  let decimal = +decimalStr;
+  let intVal = -1;
+  let remainder = 0;
+
+  // step 1. generate decimal equilavent.
+  let snafuArr = [];
+  while (decimal > 0) {
+    intVal = Math.floor(decimal / 5);
+    remainder = decimal % 5;
+    decimal = intVal;
+    snafuArr.unshift(remainder);
+  }
+  // pad an extra 0 at the end.
+  snafuArr.unshift(0);
+
+  // step 2. encode 3 and 4.
+  let pos = snafuArr.length - 1;
+  while (pos >= 0) {
+    const digit = snafuArr[pos];
+    switch (digit) {
+      case 3:
+        snafuArr[pos] = '=';
+        snafuArr[pos - 1] = snafuArr[pos - 1] + 1;
+        break;
+      case 4:
+        snafuArr[pos] = '-';
+        snafuArr[pos - 1] = snafuArr[pos - 1] + 1;
+        break;
+      case 5:
+        snafuArr[pos] = 0;
+        snafuArr[pos - 1] = snafuArr[pos - 1] + 1;
+        break;
+      default:
+        break;
+    }
+    pos -= 1;
+  }
+
+  if (snafuArr[0] === 0) snafuArr = snafuArr.slice(1);
+  return snafuArr.join('');
+};
+
+module.exports = { day25a, day25b };
diff --git a/index.js b/index.js
index bd9f086..1256f6e 100644
--- a/index.js
+++ b/index.js
@@ -23,6 +23,7 @@ const { day22a } = require('./day22');
 const { day22b } = require('./day22b');
 const { day23a, day23b } = require('./day23');
 const { day24a, day24b } = require('./day24');
+const { day25a, day25b } = require('./day25');
 
 // day1a();
 // day1b();
@@ -70,5 +71,7 @@ const { day24a, day24b } = require('./day24');
 // day22b();   // not solved.
 // day23a();
 // day23b();
-day24a();
-day24b();
\ No newline at end of file
+// day24a();
+// day24b();
+day25a();
+day25b();
\ No newline at end of file