robot-simulator

config.json

@@ -141,6 +141,14 @@
         "practices": [],
         "prerequisites": [],
         "difficulty": 3
+      },
+      {
+        "slug": "robot-simulator",
+        "name": "Robot Simulator",
+        "uuid": "26025a1c-21b8-428b-80a1-6068fbdf7834",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 3
       }
     ]
   },

exercises/practice/robot-simulator/.docs/instructions.md

@@ -0,0 +1,25 @@
+# Instructions
+
+Write a robot simulator.
+
+A robot factory's test facility needs a program to verify robot movements.
+
+The robots have three possible movements:
+
+- turn right
+- turn left
+- advance
+
+Robots are placed on a hypothetical infinite grid, facing a particular direction (north, east, south, or west) at a set of {x,y} coordinates,
+e.g., {3,8}, with coordinates increasing to the north and east.
+
+The robot then receives a number of instructions, at which point the testing facility verifies the robot's new position, and in which direction it is pointing.
+
+- The letter-string "RAALAL" means:
+  - Turn right
+  - Advance twice
+  - Turn left
+  - Advance once
+  - Turn left yet again
+- Say a robot starts at {7, 3} facing north.
+  Then running this stream of instructions should leave it at {9, 4} facing west.

exercises/practice/robot-simulator/.meta/config.json

@@ -0,0 +1,18 @@
+{
+  "authors": [
+    "quintuple-mallard"
+  ],
+  "files": {
+    "solution": [
+      "robot-simulator.nu"
+    ],
+    "test": [
+      "tests.nu"
+    ],
+    "example": [
+      ".meta/example.nu"
+    ]
+  },
+  "blurb": "Write a robot simulator.",
+  "source": "Inspired by an interview question at a famous company."
+}

exercises/practice/robot-simulator/.meta/example.nu

@@ -0,0 +1,27 @@
+const directions: list<string> = [north east south west]
+const offsets: list<list<number>> = [[0 1] [1 0] [0 -1] [-1 0]]
+def indexof [item: any]: list<any> -> number {
+  $in | enumerate | where $it.item == $item | get index.0
+}
+def advance [robot: record<position: record<x: int, y: int>, direction: string>] {
+  let change = $offsets | get ($directions | indexof $robot.direction | into cell-path)
+  $robot | update position ({x: ($robot.position.x + $change.0), y: ($robot.position.y + $change.1)})
+}
+def turnr [robot: record<position: record<x: int, y: int>, direction: string>] {
+  let idx = $directions | indexof $robot.direction
+  $robot | update direction ($directions | get (($idx + 1) mod 4 | into cell-path))
+}
+def turnl [robot: record<position: record<x: int, y: int>, direction: string>] {
+  let idx = $directions | indexof $robot.direction
+  $robot | update direction ($directions | get (($idx - 1) mod 4 | into cell-path))
+}
+export def run [instructions: string]: record<position: record<x: int, y: int>, direction: string> -> record<position: record<x: int, y: int>, direction: string> {
+  let robot = $in
+  $instructions | split chars | reduce --fold $robot {|c, robot|
+    match $c {
+      "A" => (advance $robot),
+      "R" => (turnr $robot),
+      "L" => (turnl $robot),
+    }
+  }
+}

exercises/practice/robot-simulator/.meta/tests.toml

@@ -0,0 +1,66 @@
+# 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.
+
+[c557c16d-26c1-4e06-827c-f6602cd0785c]
+description = "Create robot -> at origin facing north"
+include = false
+
+[bf0dffce-f11c-4cdb-8a5e-2c89d8a5a67d]
+description = "Create robot -> at negative position facing south"
+include = false
+
+[8cbd0086-6392-4680-b9b9-73cf491e67e5]
+description = "Rotating clockwise -> changes north to east"
+
+[8abc87fc-eab2-4276-93b7-9c009e866ba1]
+description = "Rotating clockwise -> changes east to south"
+
+[3cfe1b85-bbf2-4bae-b54d-d73e7e93617a]
+description = "Rotating clockwise -> changes south to west"
+
+[5ea9fb99-3f2c-47bd-86f7-46b7d8c3c716]
+description = "Rotating clockwise -> changes west to north"
+
+[fa0c40f5-6ba3-443d-a4b3-58cbd6cb8d63]
+description = "Rotating counter-clockwise -> changes north to west"
+
+[da33d734-831f-445c-9907-d66d7d2a92e2]
+description = "Rotating counter-clockwise -> changes west to south"
+
+[bd1ca4b9-4548-45f4-b32e-900fc7c19389]
+description = "Rotating counter-clockwise -> changes south to east"
+
+[2de27b67-a25c-4b59-9883-bc03b1b55bba]
+description = "Rotating counter-clockwise -> changes east to north"
+
+[f0dc2388-cddc-4f83-9bed-bcf46b8fc7b8]
+description = "Moving forward one -> facing north increments Y"
+
+[2786cf80-5bbf-44b0-9503-a89a9c5789da]
+description = "Moving forward one -> facing south decrements Y"
+
+[84bf3c8c-241f-434d-883d-69817dbd6a48]
+description = "Moving forward one -> facing east increments X"
+
+[bb69c4a7-3bbf-4f64-b415-666fa72d7b04]
+description = "Moving forward one -> facing west decrements X"
+
+[e34ac672-4ed4-4be3-a0b8-d9af259cbaa1]
+description = "Follow series of instructions -> moving east and north from README"
+
+[f30e4955-4b47-4aa3-8b39-ae98cfbd515b]
+description = "Follow series of instructions -> moving west and north"
+
+[3e466bf6-20ab-4d79-8b51-264165182fca]
+description = "Follow series of instructions -> moving west and south"
+
+[41f0bb96-c617-4e6b-acff-a4b279d44514]
+description = "Follow series of instructions -> moving east and north"

exercises/practice/robot-simulator/robot-simulator.nu

@@ -0,0 +1,4 @@
+export def run [instructions: string]: record<position: record<x: int, y: int>, direction: string> -> record<position: record<x: int, y: int>, direction: string> {
+  error make {msg: "Remove this line and implement grep"}
+  {position: {x: 0, y: 0}, direction: north}
+}

exercises/practice/robot-simulator/tests.nu

@@ -0,0 +1,49 @@
+use robot-simulator.nu run
+use std/assert
+# changes north to east
+assert equal ({position: {x: 0, y: 0}, direction: north} | run R) {position: {x: 0, y: 0}, direction: east}
+
+# changes east to south
+assert equal ({position: {x: 0, y: 0}, direction: east} | run R) {position: {x: 0, y: 0}, direction: south}
+
+# changes south to west
+assert equal ({position: {x: 0, y: 0}, direction: south} | run R) {position: {x: 0, y: 0}, direction: west}
+
+# changes west to north
+assert equal ({position: {x: 0, y: 0}, direction: west} | run R) {position: {x: 0, y: 0}, direction: north}
+
+# changes north to west
+assert equal ({position: {x: 0, y: 0}, direction: north} | run L) {position: {x: 0, y: 0}, direction: west}
+
+# changes west to south
+assert equal ({position: {x: 0, y: 0}, direction: west} | run L) {position: {x: 0, y: 0}, direction: south}
+
+# changes south to east
+assert equal ({position: {x: 0, y: 0}, direction: south} | run L) {position: {x: 0, y: 0}, direction: east}
+
+# changes east to north
+assert equal ({position: {x: 0, y: 0}, direction: east} | run L) {position: {x: 0, y: 0}, direction: north}
+
+# facing north increments Y
+assert equal ({position: {x: 0, y: 0}, direction: north} | run A) {position: {x: 0, y: 1}, direction: north}
+
+# facing south decrements Y
+assert equal ({position: {x: 0, y: 0}, direction: south} | run A) {position: {x: 0, y: -1}, direction: south}
+
+# facing east increments X
+assert equal ({position: {x: 0, y: 0}, direction: east} | run A) {position: {x: 1, y: 0}, direction: east}
+
+# facing west decrements X
+assert equal ({position: {x: 0, y: 0}, direction: west} | run A) {position: {x: -1, y: 0}, direction: west}
+
+# moving east and north from README
+assert equal ({position: {x: 7, y: 3}, direction: north} | run RAALAL) {position: {x: 9, y: 4}, direction: west}
+
+# moving west and north
+assert equal ({position: {x: 0, y: 0}, direction: north} | run LAAARALA) {position: {x: -4, y: 1}, direction: west}
+
+# moving west and south
+assert equal ({position: {x: 2, y: -7}, direction: east} | run RRAAAAALA) {position: {x: -3, y: -8}, direction: south}
+
+# moving east and north
+assert equal ({position: {x: 8, y: 4}, direction: south} | run LAAARRRALLLL) {position: {x: 11, y: 5}, direction: north}