Implement exercise 'collatz-conjecture'

config.json

@@ -124,6 +124,14 @@
         "prerequisites": [],
         "difficulty": 2
       },
+      {
+        "slug": "collatz-conjecture",
+        "name": "Collatz Conjecture",
+        "uuid": "dd18fd4d-21de-40f8-9d92-2c5a1d1e7133",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 2
+      },
       {
         "slug": "difference-of-squares",
         "name": "Difference of Squares",

config.yaml

@@ -121,6 +121,13 @@ exercises:
     prerequisites: []
     difficulty: 2
 
+  - slug: collatz-conjecture
+    name: Collatz Conjecture
+    uuid: dd18fd4d-21de-40f8-9d92-2c5a1d1e7133
+    practices: []
+    prerequisites: []
+    difficulty: 2
+
   - slug: difference-of-squares
     name: Difference of Squares
     uuid: de0c68d4-f0c3-4bb7-9ab2-378f9034bc82

exercises/practice/collatz-conjecture/.docs/instructions.md

@@ -0,0 +1,29 @@
+# Instructions
+
+The Collatz Conjecture or 3x+1 problem can be summarized as follows:
+
+Take any positive integer n.
+If n is even, divide n by 2 to get n / 2.
+If n is odd, multiply n by 3 and add 1 to get 3n + 1.
+Repeat the process indefinitely.
+The conjecture states that no matter which number you start with, you will always reach 1 eventually.
+
+Given a number n, return the number of steps required to reach 1.
+
+## Examples
+
+Starting with n = 12, the steps would be as follows:
+
+0. 12
+1. 6
+2. 3
+3. 10
+4. 5
+5. 16
+6. 8
+7. 4
+8. 2
+9. 1
+
+Resulting in 9 steps.
+So for input n = 12, the return value would be 9.

exercises/practice/collatz-conjecture/.meta/.yamlscript/exercise.mk

@@ -0,0 +1 @@
+YS_VERSION := 0.1.75

exercises/practice/collatz-conjecture/.meta/Makefile

@@ -0,0 +1,28 @@
+SHELL := bash
+
+BASE := $(shell pwd)
+
+export YS_VERSION := 0.1.76
+
+YS_LOCAL_PREFIX := ../../../../.local/v$(YS_VERSION)
+
+YS_LOCAL_BIN := $(YS_LOCAL_PREFIX)/bin
+
+YS_BIN := $(YS_LOCAL_BIN)/ys-$(YS_VERSION)
+
+TEST_FILE ?= $(wildcard *-test.ys)
+
+
+export PATH := $(YS_LOCAL_BIN):$(PATH)
+
+export YSPATH := $(BASE)
+
+
+default:
+
+test: $(YS_BIN)
+	prove -v $(TEST_FILE)
+
+$(YS_BIN):
+	curl -s https://yamlscript.org/install | \
+	  BIN=1 VERSION=$(YS_VERSION) PREFIX=$(YS_LOCAL_PREFIX) bash >/dev/null

exercises/practice/collatz-conjecture/.meta/collatz-conjecture-test.ys

@@ -0,0 +1,40 @@
+#!/usr/bin/env ys-0
+
+require ys::taptest: :all
+
+use: collatz-conjecture
+
+test::
+- name: Zero steps for one
+  code: steps(1)
+  want: 0
+  uuid: 540a3d51-e7a6-47a5-92a3-4ad1838f0bfd
+
+- name: Divide if even
+  code: steps(16)
+  want: 4
+  uuid: 3d76a0a6-ea84-444a-821a-f7857c2c1859
+
+- name: Even and odd steps
+  code: steps(12)
+  want: 9
+  uuid: 754dea81-123c-429e-b8bc-db20b05a87b9
+
+- name: Large number of even and odd steps
+  code: steps(1000000)
+  want: 152
+  uuid: ecfd0210-6f85-44f6-8280-f65534892ff6
+
+- name: Zero is an error
+  code: steps(0)
+  what: error
+  want: Only positive integers are allowed
+  uuid: 2187673d-77d6-4543-975e-66df6c50e2da
+
+- name: Negative value is an error
+  code: steps(-15)
+  what: error
+  want: Only positive integers are allowed
+  uuid: ec11f479-56bc-47fd-a434-bcd7a31a7a2e
+
+done: 6

exercises/practice/collatz-conjecture/.meta/collatz-conjecture.ys

@@ -0,0 +1,11 @@
+!yamlscript/v0
+
+defn steps(number):
+  when-not pos?(number):
+    die('Only positive integers are allowed')
+
+  loop num number, steps 0:
+    cond:
+      num == 1:   steps
+      even?(num): recur((num / 2), steps.++)
+      else:       recur((num * 3).++, steps.++)

exercises/practice/collatz-conjecture/.meta/config.json

@@ -0,0 +1,23 @@
+{
+  "authors": [
+    "ingydotnet"
+  ],
+  "files": {
+    "solution": [
+      "collatz-conjecture.ys"
+    ],
+    "test": [
+      "collatz-conjecture-test.ys",
+      "GNUmakefile",
+      "Makefile",
+      ".yamlscript/exercise.mk",
+      ".yamlscript/exercism-ys-installer"
+    ],
+    "example": [
+      ".meta/collatz-conjecture.ys"
+    ]
+  },
+  "blurb": "Calculate the number of steps to reach 1 using the Collatz conjecture.",
+  "source": "An unsolved problem in mathematics named after mathematician Lothar Collatz",
+  "source_url": "https://en.wikipedia.org/wiki/3x_%2B_1_problem"
+}

exercises/practice/collatz-conjecture/.meta/tests.toml

@@ -0,0 +1,38 @@
+# This is an auto-generated file.
+#
+# Regenerating this file via `configlet sync` will:
+# - Recreate every `description` key/value pair
+# - Recreate every `reimplements` key/value pair, where they exist in problem-specifications
+# - Remove any `include = true` key/value pair (an omitted `include` key implies inclusion)
+# - Preserve any other key/value pair
+#
+# As user-added comments (using the # character) will be removed when this file
+# is regenerated, comments can be added via a `comment` key.
+
+[540a3d51-e7a6-47a5-92a3-4ad1838f0bfd]
+description = "zero steps for one"
+
+[3d76a0a6-ea84-444a-821a-f7857c2c1859]
+description = "divide if even"
+
+[754dea81-123c-429e-b8bc-db20b05a87b9]
+description = "even and odd steps"
+
+[ecfd0210-6f85-44f6-8280-f65534892ff6]
+description = "large number of even and odd steps"
+
+[7d4750e6-def9-4b86-aec7-9f7eb44f95a3]
+description = "zero is an error"
+include = false
+
+[2187673d-77d6-4543-975e-66df6c50e2da]
+description = "zero is an error"
+reimplements = "7d4750e6-def9-4b86-aec7-9f7eb44f95a3"
+
+[c6c795bf-a288-45e9-86a1-841359ad426d]
+description = "negative value is an error"
+include = false
+
+[ec11f479-56bc-47fd-a434-bcd7a31a7a2e]
+description = "negative value is an error"
+reimplements = "c6c795bf-a288-45e9-86a1-841359ad426d"

exercises/practice/collatz-conjecture/.yamlscript/exercise.mk

@@ -0,0 +1 @@
+YS_VERSION := 0.1.75

exercises/practice/collatz-conjecture/.yamlscript/exercism-ys-installer

@@ -0,0 +1,127 @@
+#!/env/bin/env bash
+
+set -euo pipefail
+
+intro-prompt() (
+  cat <<...
+--------------------------------------------------------------------------------
+
+This YAMLScript Exercism exercise requires the YAMLScript version $version
+interpreter command file to be installed here:
+
+  $prefix/bin/ys
+
+You can install it by pressing Enter now, or by running this command:
+
+  $make install-ys
+
+This should only take a few seconds and you only need to do this once.
+Other exercises will use the same file.
+
+See https://yamlscript.org/doc/install/ for more YAMLScript installation info.
+
+--------------------------------------------------------------------------------
+
+Would you like to install the 'ys' file now?
+
+...
+
+  printf "Press Enter to install. Ctl-C to Quit."; read -r
+)
+
+main() {
+  setup "$@"
+
+  install-from-local
+
+  $auto && intro-prompt
+
+  installed || install-from-release || true
+  installed || install-from-build || true
+  installed ||
+    die "Installing '$installed' failed. Giving up." \
+        "Consider filing an issue at: $gh_issue_url"
+
+  echo
+  echo 'Success!'
+  echo "$installed is now installed."
+  echo
+}
+
+installed() {
+  [[ -f $installed ]]
+}
+
+install-from-local() {
+  local path
+  path=$(command -v "$ysfq") || true
+  if [[ -f $path ]]; then
+    mkdir -p "$bin"
+    cp "$path" "$bin"/
+    ln -fs "$ysfq" "$bin/ys-0"
+    ln -fs "$ysfq" "$bin/ys"
+    (installed && $auto) && exit
+    true
+  fi
+}
+
+install-from-release() (
+  set -x
+  curl -s https://yamlscript.org/install |
+    BIN=1 VERSION="$version" PREFIX="$prefix" bash
+)
+
+install-from-build() (
+  cat <<...
+
+The binary release installation failed.
+We can attempt to build and install $ysfq now.
+This can take from 1 to 5 minutes to complete.
+
+...
+
+  printf "Press Enter to install. Ctl-C to Quit."; read -r
+
+  [[ -d /tmp && -w /tmp ]] ||
+    die "Can't write to /tmp" \
+        'Giving up.'
+
+  set -x
+
+  rm -fr "$yamlscript_clone"
+
+  git clone --branch="$version" "$yamlscript_repo" "$yamlscript_clone"
+
+  "$make" -C "$yamlscript_clone/ys" install PREFIX="$prefix"
+)
+
+setup() {
+  version=$1
+  prefix=$2
+  make=$3
+  auto=false
+  [[ ${4-} ]] && auto=true
+
+  [[ $version =~ ^0\.1\.[0-9]+$ ]] ||
+    die "Invalid YS_VERSION '$version'"
+
+  bin=$prefix/bin
+  ysfq=ys-$version
+  installed=$bin/$ysfq
+
+  if installed; then
+    echo "'$installed' is already installed."
+    exit
+  fi
+
+  yamlscript_repo=https://github.com/yaml/yamlscript
+  yamlscript_clone=/tmp/yamlscript-exercism
+  gh_issue_url=https://github.com/exercism/yamlscript/issues
+}
+
+die() {
+  printf '%s\n' "$@" >&2
+  exit 1
+}
+
+main "$@"

exercises/practice/collatz-conjecture/GNUmakefile

@@ -0,0 +1,49 @@
+SHELL := bash
+
+BASE := $(shell pwd)
+
+export YS_VERSION := 0.1.76
+
+YS_LOCAL_PREFIX := ../../../.local/v$(YS_VERSION)
+ifeq (,$(shell [[ -d "$(YS_LOCAL_PREFIX)" ]] && echo ok))
+YS_LOCAL_PREFIX := $(shell cd .. && pwd -P)/.local/v$(YS_VERSION)
+endif
+
+YS_LOCAL_BIN := $(YS_LOCAL_PREFIX)/bin
+YS_BIN := $(YS_LOCAL_BIN)/ys-$(YS_VERSION)
+
+YS_INSTALLER := .yamlscript/exercism-ys-installer
+YS_INSTALLER_CMD := \
+  bash $(YS_INSTALLER) $(YS_VERSION) $(YS_LOCAL_PREFIX) $(MAKE)
+
+TEST_FILE ?= $(wildcard *-test.ys)
+
+export PATH := $(YS_LOCAL_BIN):$(PATH)
+export YSPATH := $(BASE)
+
+
+#-------------------------------------------------------------------------------
+default:
+	@echo " No default make rule. Try 'make test'."
+
+test: $(YS_BIN)
+	prove -v $(TEST_FILE)
+
+install-ys:
+	@$(YS_INSTALLER_CMD)
+
+uninstall-ys:
+	rm -fr $(YS_LOCAL_PREFIX)
+
+
+#-------------------------------------------------------------------------------
+ifdef EXERCISM_YAMLSCRIPT_GHA
+$(YS_BIN):
+
+else ifeq (/mnt/,$(dir $(BASE)))
+$(YS_BIN):
+
+else
+$(YS_BIN):
+	@$(YS_INSTALLER_CMD) auto
+endif

exercises/practice/collatz-conjecture/Makefile

@@ -0,0 +1,8 @@
+# This Makefile is a decoy to attempt to detect when a non-GNU make is being
+# used and alert the user.
+
+test:
+	@echo "You appear to be using a non-GNU version of the 'make' program."
+	@echo "The YAMLScript Exercism track requires you to use GNU make."
+	@echo "Please try 'make $@' again using GNU make."
+	@exit 1