added reason(able) solutions.

.gitignore

@@ -0,0 +1,112 @@
+# Logs
+logs
+*.log
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+
+# Environment
+.env
+.env.dev
+
+# Runtime data
+pids
+*.pid
+*.seed
+*.pid.lock
+
+# Directory for instrumented libs generated by jscoverage/JSCover
+lib-cov
+
+# Coverage directory used by tools like istanbul
+coverage
+
+# nyc test coverage
+.nyc_output
+
+# Grunt intermediate storage (http://gruntjs.com/creating-plugins#storing-task-files)
+.grunt
+
+# Bower dependency directory (https://bower.io/)
+bower_components
+
+# node-waf configuration
+.lock-wscript
+
+# build files
+build
+lib
+es
+dist
+
+# Dependency directories
+node_modules/
+jspm_packages/
+
+# Typescript v1 declaration files
+typings/
+
+# Optional npm cache directory
+.npm
+
+# Optional eslint cache
+.eslintcache
+
+# Optional REPL history
+.node_repl_history
+
+# Output of 'npm pack'
+*.tgz
+
+# Yarn Integrity file
+.yarn-integrity
+
+# General
+*.DS_Store
+.AppleDouble
+.LSOverride
+
+# Icon must end with two \r
+Icon
+
+# Thumbnails
+._*
+
+# Files that might appear in the root of a volume
+.DocumentRevisions-V100
+.fseventsd
+.Spotlight-V100
+.TemporaryItems
+.Trashes
+.VolumeIcon.icns
+.com.apple.timemachine.donotpresent
+
+# Directories potentially created on remote AFP share
+.AppleDB
+.AppleDesktop
+Network Trash Folder
+Temporary Items
+.apdisk
+
+# Windows thumbnail cache files
+Thumbs.db
+ehthumbs.db
+ehthumbs_vista.db
+
+# Dump file
+*.stackdump
+
+# Folder config file
+Desktop.ini
+
+# Recycle Bin used on file shares
+$RECYCLE.BIN/
+
+# Windows Installer files
+*.cab
+*.msi
+*.msm
+*.msp
+
+# Windows shortcuts
+*.lnk

.merlin

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+####{BSB GENERATED: NO EDIT
+FLG -ppx /Users/shriyans/Projects/reason/99.re/node_modules/bs-platform/bin/bsppx.exe
+S /Users/shriyans/Projects/reason/99.re/node_modules/bs-platform/lib/ocaml
+B /Users/shriyans/Projects/reason/99.re/node_modules/bs-platform/lib/ocaml
+FLG -nostdlib -no-alias-deps -color always
+FLG -w -30-40+6+7+27+32..39+44+45+101
+S src
+B lib/bs/src
+####BSB GENERATED: NO EDIT}

README.md

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+# 99 Problems
+
+Solutions to 99 Problems implemented in [Reason](https://reasonml.github.io/).
+
+[ninety-nine lisp problems]: http://www.ic.unicamp.br/~meidanis/courses/mc336/2006s2/funcional/L-99_Ninety-Nine_Lisp_Problems.html
+
+## Status
+
+Currently in progress.
+
+### Working with lists
+
+| No. | Description          | Solution                |     | No. | Description        | Solution                |
+| --- | -------------------- | ----------------------- | --- | --- | ------------------ | ----------------------- |
+| 01  | Last element         | [completed](src/p01.re) |     | 15  | Replicate          | [completed](src/p15.re) |
+| 02  | Last two elements    | [completed](src/p02.re) |     | 16  | Drop every N'th    | [completed](src/p16.re) |
+| 03  | K'th element         | [completed](src/p03.re) |     | 17  | Split              | [completed](src/p17.re) |
+| 04  | Length               | [completed](src/p04.re) |     | 18  | Slice              | [completed](src/p18.re) |
+| 05  | Reverse              | [completed](src/p05.re) |     | 19  | Rotate             | [completed](src/p19.re) |
+| 06  | Palindrome           | [completed](src/p06.re) |     | 20  | Remove             | [completed](src/p20.re) |
+| 07  | Flatten              | [completed](src/p07.re) |     | 21  | Insert             | [completed](src/p21.re) |
+| 08  | Eliminate duplicates | [completed](src/p08.re) |     | 22  | Range              | [completed](src/p22.re) |
+| 09  | Pack duplicates      | [completed](src/p09.re) |     | 23  | Random select      | [completed](src/p23.re) |
+| 10  | Run-length           | [completed](src/p10.re) |     | 24  | Random numbers     | [completed](src/p24.re) |
+| 11  | Modified run-length  | [completed](src/p11.re) |     | 25  | Random permutation | [completed](src/p25.re) |
+| 12  | Decode run-length    | [completed](src/p12.re) |     | 26  | Combinations       | [completed](src/p26.re) |
+| 13  | Direct run-length    | [completed](src/p13.re) |     | 27  | Group              | [completed](src/p27.re) |
+| 14  | Duplicate            | [completed](src/p14.re) |     | 28  | Sort by length     | [completed](src/p28.re) |
+
+### Arithmetic
+
+| No. | Description          | Solution                |     | No. | Description           | Solution                |
+| --- | -------------------- | ----------------------- | --- | --- | --------------------- | ----------------------- |
+| 31  | Prime                | [completed](src/p31.re) |     | 37  | Improve 32            | [completed](src/p37.re) |
+| 32  | GCD                  | [completed](src/p32.re) |     | 38  | Compare 32 and 35     | [completed](src/p38.re) |
+| 33  | Coprime              | [completed](src/p33.re) |     | 39  | List prime numbers    | [completed](src/p39.re) |
+| 34  | Euler's totient      | [completed](src/p34.re) |     | 40  | Goldbach's conjecture | [completed](src/p40.re) |
+| 35  | Prime factors        | [completed](src/p35.re) |     | 41  | Goldbach compositions | [completed](src/p41.re) |
+| 36  | Prime factors (pair) | [completed](src/p36.re) |     |     |                       |                         |
+
+### Logic and Codes
+
+| No. | Description                              | Solution                                   |
+| --- | ---------------------------------------- | ------------------------------------------ |
+| 46  | Truth tables for logical expressions     | [completed](src/p46.re)                    |
+| 47  | Truth tables for logical expressions (2) | [completed (combined with 46)](src/p46.re) |
+| 48  | Truth tables for logical expressions (3) | [completed](src/p48.re)                    |
+| 49  | Gray code                                | [completed](src/p49.re)                    |
+| 50  | Huffman code                             | [completed](src/p50.re)                    |
+
+### Binary Trees
+
+| No. | Description         | Solution                    |     | No. | Description              | Solution                 |
+| --- | ------------------- | --------------------------- | --- | --- | ------------------------ | ------------------------ |
+| 54A | Check Binary Tree   | **No need as type checked** |     | 62  | Collect internals        | [completed](src/p62.re)  |
+| 55  | Completely balanced | [completed](src/p55.re)     |     | 62B | Collect nodes at a level | [completed](src/p62b.re) |
+| 56  | Symmetric           | [completed](src/p56.re)     |     | 63  | Complete binary tree     | [completed](src/p63.re)  |
+| 57  | Binary search trees | [completed](src/p57.re)     |     | 64  | Layout 1                 | [completed](src/p64.re)  |
+| 58  | Generate-and-test   | [completed](src/p58.re)     |     | 65  | Layout 2                 | [completed](src/p65.re)  |
+| 59  | Height-balanced     | [completed](src/p59.re)     |     | 66  | Layout 3                 | [completed](src/p66.re)  |
+| 60  | 48 with N nodes     | [completed](src/p60.re)     |     | 67A | Stringify                | [completed](src/p67.re)  |
+| 61  | Count leaves        | [completed](src/p61.re)     |     | 68  | Preorder and inorder     | [completed](src/p68.re)  |
+| 61A | Collect leaves      | [completed](src/p61a.re)    |     | 69  | Dotstring                | [completed](src/p69.re)  |
+
+### Multiway Trees
+
+| No. | Description          | Solution                    |
+| --- | -------------------- | --------------------------- |
+| 70B | Check Multiway Tree  | **No need as type checked** |
+| 70C | Count nodes          | [completed](src/p70c.re)    |
+| 70  | Node string          | [completed](src/p70.re)     |
+| 71  | Internal path length | [completed](src/p71.re)     |
+| 72  | Bottom-up order      | [completed](src/p72.re)     |
+| 73  | Lisp-like tree       | [completed](src/p73.re)     |
+
+### Graphs
+
+| No. | Description           | Solution                |     | No. | Description           | Solution                |
+| --- | --------------------- | ----------------------- | --- | --- | --------------------- | ----------------------- |
+| 80  | Conversions           | [completed](src/p80.re) |     | 85  | Graph isomorphism     | [completed](src/p85.re) |
+| 81  | Path                  | [completed](src/p81.re) |     | 86  | Graph coloration      | [completed](src/p86.re) |
+| 82  | Cycle                 | [completed](src/p82.re) |     | 87  | Depth-first traversal | [completed](src/p87.re) |
+| 83  | Spanning trees        | [completed](src/p83.re) |     | 88  | Connected components  | [completed](src/p88.re) |
+| 84  | Minimal spanning tree | [completed](src/p84.re) |     | 89  | Bipartite graphs      | Not implemented         |
+
+### Miscellaneous Problems
+
+| No. | Description             | Solution                |     | No. | Description          | Solution                |
+| --- | ----------------------- | ----------------------- | --- | --- | -------------------- | ----------------------- |
+| 90  | Eight queens problem    | [completed](src/p90.re) |     | 95  | English number words | [completed](src/p95.re) |
+| 91  | Knight's tour           | [completed](src/p91.re) |     | 96  | Syntax checker       | [completed](src/p96.re) |
+| 92  | Von Koch's conjecture   | [completed](src/p92.re) |     | 97  | Sudoku               | [completed](src/p97.re) |
+| 93  | An arithmetic puzzle    | [completed](src/p93.re) |     | 98  | Nonograms            | [completed](src/p98.re) |
+| 94  | K-regular simple graphs | [completed](src/p94.re) |     | 99  | Crossword puzzle     | Not implemented         |
+
+## Acknowledgement
+
+### References
+
+-   [99 Problems in OCaml](https://ocaml.org/learn/tutorials/99problems.html)
+
+### Insipration
+
+-   [99 Problems in Haskell](https://wiki.haskell.org/H-99:_Ninety-Nine_Haskell_Problems)
+-   [99 Problems in Lisp](https://www.ic.unicamp.br/~meidanis/courses/mc336/2006s2/funcional/L-99_Ninety-Nine_Lisp_Problems.html)
+-   [99 Problems in Prolog](https://sites.google.com/site/prologsite/prolog-problems)

bsconfig.json

@@ -0,0 +1,7 @@
+{
+  "name": "99.re",
+  "sources": ["src"],
+  "bsc-flags": ["-bs-super-errors"],
+  "package-specs": "commonjs",
+  "refmt": 3
+}

package.json

@@ -0,0 +1,20 @@
+{
+  "private": true,
+  "name": "99.re",
+  "description": "99 problems with (reason)able solutions.",
+  "scripts": {
+    "clean": "bsb -clean-world",
+    "build": "bsb -make-world",
+    "watch": "bsb -make-world -w"
+  },
+  "keywords": [
+    "99 problems",
+    "reasonML",
+    "bucklescript"
+  ],
+  "author": "Shriyans Bhatnagar <shriyansbhatnagar@gmail.com>",
+  "license": "MIT",
+  "devDependencies": {
+    "bs-platform": "^2.0.0"
+  }
+}

src/p01.re

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+/* Find the last element of a list. */
+let rec last = (list) =>
+  switch list {
+  | [] => None
+  | [x] => Some(x)
+  | [_, ...xs] => last(xs)
+  };

src/p02.re

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+/* Find the last but one element of a list. */
+let rec last_but_one = (list) =>
+  switch list {
+  | []
+  | [_] => None
+  | [x, y] => Some((x, y))
+  | [_, ...xs] => last_but_one(xs)
+  };

src/p03.re

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+/* Find the K'th element of a list. The first element in the list is number 1. */
+let rec element_at = (k, list) =>
+  switch list {
+  | [] => None
+  | [x, ...xs] => k == 1 ? Some(x) : element_at(k - 1, xs)
+  };

src/p04.re

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+/* Find the number of elements of a list. */
+let rec length = (list) =>
+  switch list {
+  | [] => 0
+  | [_, ...xs] => 1 + length(xs)
+  };

src/p05.re

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+/* Reverse a list. */
+let reverse = (list) => {
+  let rec aux = (acc, list) =>
+    switch list {
+    | [] => acc
+    | [x, ...xs] => aux([x, ...acc], xs)
+    };
+  aux([], list)
+};

src/p06.re

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+/* Find out whether a list is a palindrome. */
+/* either use the reverse function from the problem 05, or use the
+   built-in List.rev  */
+let is_palindrome = (xs) => xs == List.rev(xs);

src/p07.re

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+/* Flatten a nested list structure. */
+type node('a) =
+  | One('a)
+  | Many(list(node('a)));
+
+let flatten = (list) => {
+  let rec aux = (acc, list) =>
+    switch list {
+    | [] => acc
+    | [One(x), ...xs] => aux([x, ...acc], xs)
+    | [Many(x), ...xs] => aux(aux(acc, x), xs)
+    };
+  List.rev(aux([], list))
+};

src/p08.re

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+/* Eliminate consecutive duplicates of list elements. */
+let rec compress = (list) =>
+  switch list {
+  | [] => []
+  | [x] => [x]
+  | [x, ...[y, ..._] as z] => x == y ? compress(z) : [x, ...compress(z)]
+  };

src/p09.re

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+/*  Pack consecutive duplicates of list elements into sublists. */
+let pack = (list) => {
+  let rec aux = (curr, acc, list) =>
+    switch list {
+    | [] => []
+    | [x] => [[x, ...curr], ...acc]
+    | [x, ...[y, ..._] as z] =>
+      x == y ? aux([x, ...curr], acc, z) : aux([], [[x, ...curr], ...acc], z)
+    };
+  List.rev(aux([], [], list))
+};

src/p10.re

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+/* Run-length encoding of a list. */
+let encode = (list) => {
+  let rec aux = (count, acc, list) =>
+    switch list {
+    | [] => []
+    | [x] => [(count + 1, x), ...acc]
+    | [x, ...[y, ..._] as z] =>
+      x == y ? aux(count + 1, acc, z) : aux(0, [(count + 1, x), ...acc], z)
+    };
+  List.rev(aux(0, [], list))
+};

src/p11.re

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+/* Modified run-length encoding. */
+type rle('a) =
+  | One('a)
+  | Many(int, 'a);
+
+let modified_encode = (list) => {
+  let create_tuple = (count, elem) => count == 1 ? One(elem) : Many(count, elem);
+  let rec aux = (count, acc, list) =>
+    switch list {
+    | [] => []
+    | [x] => [create_tuple(count + 1, x), ...acc]
+    | [x, ...[y, ..._] as z] =>
+      x == y ? aux(count + 1, acc, z) : aux(0, [create_tuple(count + 1, x), ...acc], z)
+    };
+  List.rev(aux(0, [], list))
+};

src/p12.re

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+/* Decode a run-length encoded list. */
+type rle('a) =
+  | One('a)
+  | Many(int, 'a);
+
+let decode = (list) => {
+  let rec many = (acc, n, x) => n == 0 ? acc : many([x, ...acc], n - 1, x);
+  let rec aux = (acc, list) =>
+    switch list {
+    | [] => []
+    | [One(x), ...xs] => aux([x, ...acc], xs)
+    | [Many(n, x), ...xs] => aux(many(acc, n, x), xs)
+    };
+  aux([], List.rev(list))
+};