Add new exercise: prism (#339)

* Add new exercise: prism

* Drop a space after the `#`

* Quote `"true"`

* Put the ID first

* Sort prisms by id

Author: IsaacG

config.json

@@ -540,6 +540,14 @@
         "prerequisites": [],
         "difficulty": 4
       },
+      {
+        "slug": "prism",
+        "name": "Prism",
+        "uuid": "865a0901-4bdf-44c5-a0e9-5b87c104cb9d",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 4
+      },
       {
         "slug": "roman-numerals",
         "name": "Roman Numerals",

exercises/practice/prism/.docs/instructions.md

@@ -0,0 +1,36 @@
+# Instructions
+
+Before activating the laser array, you must predict the exact order in which crystals will be hit, identified by their sample IDs.
+
+## Example Test Case
+
+Consider this crystal array configuration:
+
+```json
+{
+  "start": { "x": 0, "y": 0, "angle": 0 },
+  "prisms": [
+    { "id": 3, "x": 30, "y": 10, "angle": 45 },
+    { "id": 1, "x": 10, "y": 10, "angle": -90 },
+    { "id": 2, "x": 10, "y": 0, "angle": 90 },
+    { "id": 4, "x": 20, "y": 0, "angle": 0 }
+  ]
+}
+```
+
+## What's Happening
+
+The laser starts at the origin `(0, 0)` and fires horizontally to the right at angle 0°.
+Here's the step-by-step beam path:
+
+**Step 1**: The beam travels along the x-axis (y = 0) and first encounters **Crystal #2** at position `(10, 0)`.
+This crystal has a refraction angle of 90°, which means it bends the beam perpendicular to its current path.
+The beam, originally traveling at 0°, is now redirected to 90° (straight up).
+
+**Step 2**: The beam now travels vertically upward from position `(10, 0)` and strikes **Crystal #1** at position `(10, 10)`.
+This crystal has a refraction angle of -90°, bending the beam by -90° relative to its current direction.
+The beam was traveling at 90°, so after refraction it's now at 0° (90° + (-90°) = 0°), traveling horizontally to the right again.
+
+**Step 3**: From position `(10, 10)`, the beam travels horizontally and encounters **Crystal #3** at position `(30, 10)`.
+This crystal refracts the beam by 45°, changing its direction to 45°.
+The beam continues into empty space beyond the array.

exercises/practice/prism/.docs/introduction.md

@@ -0,0 +1,5 @@
+# Introduction
+
+You're a researcher at **PRISM** (Precariously Redirected Illumination Safety Management), working with a precision laser calibration system that tests experimental crystal prisms.
+These crystals are being developed for next-generation optical computers, and each one has unique refractive properties based on its molecular structure.
+The lab's laser system can damage crystals if they receive unexpected illumination, so precise path prediction is critical.

exercises/practice/prism/.meta/config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "IsaacG"
+  ],
+  "files": {
+    "solution": [
+      "prism.awk"
+    ],
+    "test": [
+      "test-prism.bats"
+    ],
+    "example": [
+      ".meta/example.awk"
+    ]
+  },
+  "blurb": "Calculate the path of a laser through reflective prisms.",
+  "source": "FraSanga",
+  "source_url": "https://github.com/exercism/problem-specifications/pull/2625"
+}

exercises/practice/prism/.meta/example.awk

@@ -0,0 +1,58 @@
+# The first line of input is the starting x, y and angle.
+# Any remaining input is the prisms: x, y, angle and ID.
+# The program is expected to print out prism IDs, space separated on one line.
+
+function abs(n) {
+    return (n > 0) ? n : -n
+}
+
+# Starting position
+NR == 1 { x = $1; y = $2; a = $3; }
+
+# Prism positions
+NR > 1 { prisms[$1]["x"] = $2; prisms[$1]["y"] = $3; prisms[$1]["a"] = $4; }
+
+# Compute the path
+END {
+    # Loop for hits until no more are found.
+    deg_to_rad = 3.141592 / 180
+    do {
+        found = 0
+        distance = 0
+        for (id in prisms) {
+            # Do not count a prism we just hit.
+            if (prisms[id]["x"] == x && prisms[id]["y"] == y) {
+                continue
+            }
+            dx = prisms[id]["x"] - x
+            dy = prisms[id]["y"] - y
+            r = sqrt(dx * dx + dy * dy)
+            # How close did we get to the prism?
+            hx = abs(cos(a * deg_to_rad) * r - dx)
+            hy = abs(sin(a * deg_to_rad) * r - dy)
+            if (hx < 0.1 && hy < 0.1) {
+                # Track the closest prism along the laser path
+                if (!found || r < distance) {
+                    fid = id
+                    distance = r
+                }
+                found = 1
+            }
+        }
+        if (found) {
+            x = prisms[fid]["x"]
+            y = prisms[fid]["y"]
+            a += prisms[fid]["a"]
+            out[count++] = fid
+        }
+    } while (found == 1)
+
+    # Print the prisms we hit, space separated IDs
+    if (count) {
+        res = out[0]
+        for (j = 1; j < count; j++) {
+            res = res " " out[j]
+        }
+        print res
+    }
+}

exercises/practice/prism/.meta/generate_tests

@@ -0,0 +1,45 @@
+#!/usr/bin/env bash
+
+if (( BASH_VERSINFO[0] < 4 )); then
+    echo "[Failure] This script requires bash version 4+" >&2
+    exit 1
+fi
+
+if (( $# != 1 )) || [[ ${1##*/} != canonical-data.json ]]; then
+    echo "Usage: $0 <canonical-data.json for prism>"
+    exit 1
+fi
+
+printf '%s\n' '#!/usr/bin/env bats' 'load bats-extra'
+
+jq -r '
+    .cases |
+    # Add an index to each case, similar to Python enumerate()
+    [foreach .[] as $case ({"index": 0, "case": ""}; {"index": .index + 1, "case": $case})] |
+    map(
+        [
+            "",
+            "@test \"\(.case.description)\" {",
+            # Do not skip the first test
+            if .index == 1 then
+            "    # [[ $BATS_RUN_SKIPPED == \"true\" ]] || skip"
+            else
+            "    [[ $BATS_RUN_SKIPPED == \"true\" ]] || skip"
+            end,
+            "    run gawk -f prism.awk <<EOF",
+            # Start position
+            (.case.input.start | "\(.x) \(.y) \(.angle)"),
+            # Prism list
+            if (.case.input.prisms | length > 0) then
+                (.case.input.prisms | sort_by(.id) | map("\(.id) \(.x) \(.y) \(.angle)") | join("\n"))
+            else
+                empty
+            end,
+            "EOF",
+            "    assert_success",
+            "    assert_output \"" + (.case.expected.sequence | join(" ")) + "\"",
+            "}"
+        ] |
+        join("\n")
+    )
+    | join("\n")' "$1"

exercises/practice/prism/.meta/tests.toml

@@ -0,0 +1,52 @@
+# 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.
+
+[ec65d3b3-f7bf-4015-8156-0609c141c4c4]
+description = "zero prisms"
+
+[ec0ca17c-0c5f-44fb-89ba-b76395bdaf1c]
+description = "one prism one hit"
+
+[0db955f2-0a27-4c82-ba67-197bd6202069]
+description = "one prism zero hits"
+
+[8d92485b-ebc0-4ee9-9b88-cdddb16b52da]
+description = "going up zero hits"
+
+[78295b3c-7438-492d-8010-9c63f5c223d7]
+description = "going down zero hits"
+
+[acc723ea-597b-4a50-8d1b-b980fe867d4c]
+description = "going left zero hits"
+
+[3f19b9df-9eaa-4f18-a2db-76132f466d17]
+description = "negative angle"
+
+[96dacffb-d821-4cdf-aed8-f152ce063195]
+description = "large angle"
+
+[513a7caa-957f-4c5d-9820-076842de113c]
+description = "upward refraction two hits"
+
+[d452b7c7-9761-4ea9-81a9-2de1d73eb9ef]
+description = "downward refraction two hits"
+
+[be1a2167-bf4c-4834-acc9-e4d68e1a0203]
+description = "same prism twice"
+
+[df5a60dd-7c7d-4937-ac4f-c832dae79e2e]
+description = "simple path"
+
+[8d9a3cc8-e846-4a3b-a137-4bfc4aa70bd1]
+description = "multiple prisms floating point precision"
+
+[e077fc91-4e4a-46b3-a0f5-0ba00321da56]
+description = "complex path with multiple prisms floating point precision"