Add minesweeper exercise (#681)

* Add minesweeper exercise

* consistency with space-padded operators in arithmetic expressions

config.json

@@ -1171,6 +1171,14 @@
         "practices": [],
         "prerequisites": [],
         "difficulty": 3
+      },
+      {
+        "slug": "minesweeper",
+        "name": "Minesweeper",
+        "uuid": "eae564ba-b4d9-4463-ae3f-f7f05f4e52ea",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 5
       }
     ],
     "foregone": [

exercises/practice/minesweeper/.docs/hints.md

@@ -0,0 +1,19 @@
+# Hints for Bash Minesweeper Exercise
+
+This exercise seems to require a two-dimensional array.
+Bash only offers one-dimensional indexed or associative [arrays][array].
+
+Multi-dimensional arrays can be simulated by using an associative arrays: encode the indices into a comma-separated string to use as the array key.
+
+```bash
+# store this matrix:
+#   a b
+#   c d
+declare -A array2d
+array2d["0,0"]="a"
+array2d["0,1"]="b"
+array2d["1,0"]="c"
+array2d["1,1"]="d"
+```
+
+[array]: https://www.gnu.org/software/bash/manual/bash.html#Arrays

exercises/practice/minesweeper/.docs/instructions.md

@@ -0,0 +1,26 @@
+# Instructions
+
+Your task is to add the mine counts to empty squares in a completed Minesweeper board.
+The board itself is a rectangle composed of squares that are either empty (`' '`) or a mine (`'*'`).
+
+For each empty square, count the number of mines adjacent to it (horizontally, vertically, diagonally).
+If the empty square has no adjacent mines, leave it empty.
+Otherwise replace it with the adjacent mines count.
+
+For example, you may receive a 5 x 4 board like this (empty spaces are represented here with the '·' character for display on screen):
+
+```text
+·*·*·
+··*··
+··*··
+·····
+```
+
+Which your code should transform into this:
+
+```text
+1*3*1
+13*31
+·2*2·
+·111·
+```

exercises/practice/minesweeper/.docs/introduction.md

@@ -0,0 +1,5 @@
+# Introduction
+
+[Minesweeper][wikipedia] is a popular game where the user has to find the mines using numeric hints that indicate how many mines are directly adjacent (horizontally, vertically, diagonally) to a square.
+
+[wikipedia]: https://en.wikipedia.org/wiki/Minesweeper_(video_game)

exercises/practice/minesweeper/.meta/config.json

@@ -0,0 +1,15 @@
+{
+  "authors": [],
+  "files": {
+    "solution": [
+      "minesweeper.sh"
+    ],
+    "test": [
+      "minesweeper.bats"
+    ],
+    "example": [
+      ".meta/example.sh"
+    ]
+  },
+  "blurb": "Add the numbers to a minesweeper board."
+}

exercises/practice/minesweeper/.meta/example.sh

@@ -0,0 +1,51 @@
+#!/usr/bin/env bash
+
+# some global vars
+declare -A board
+height=$#
+width=${#1}
+
+parse_input() {
+    local rownum=0 row col index char
+    for row in "$@"; do
+        for ((col = 0; col < "${#row}"; col++)); do
+            index="${rownum},${col}"
+            char=${row:col:1}
+            board[$index]=$char
+        done
+        (( rownum++ ))
+    done
+}
+
+count() {
+    local r=$1 c=$2
+    local count=0
+    for dr in -1 0 1; do
+        (( r + dr < 0 || r + dr == height )) && continue
+        for dc in -1 0 1; do
+            (( c + dc < 0 || c + dc == width )) && continue
+            (( dr == 0 && dc == 0 )) && continue
+            index="$((r + dr)),$((c + dc))"
+            [[ ${board[$index]} == "*" ]] && (( count++ ))
+        done
+    done
+    (( count == 0 )) && echo " " || echo "$count"
+}
+
+create_output() {
+    local row output col
+    for ((row = 0; row < height; row++)); do
+        output=""
+        for ((col = 0; col < width; col++)); do
+            if [[ ${board[$row,$col]} == "*" ]]; then
+                output+="*"
+            else
+                output+=$( count "$row" "$col" )
+            fi
+        done
+        echo "$output"
+    done
+}
+
+parse_input "$@"
+create_output

exercises/practice/minesweeper/.meta/tests.toml

@@ -0,0 +1,47 @@
+# 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.
+
+[0c5ec4bd-dea7-4138-8651-1203e1cb9f44]
+description = "no rows"
+include = false
+
+[650ac4c0-ad6b-4b41-acde-e4ea5852c3b8]
+description = "no columns"
+
+[6fbf8f6d-a03b-42c9-9a58-b489e9235478]
+description = "no mines"
+
+[61aff1c4-fb31-4078-acad-cd5f1e635655]
+description = "minefield with only mines"
+
+[84167147-c504-4896-85d7-246b01dea7c5]
+description = "mine surrounded by spaces"
+
+[cb878f35-43e3-4c9d-93d9-139012cccc4a]
+description = "space surrounded by mines"
+
+[7037f483-ddb4-4b35-b005-0d0f4ef4606f]
+description = "horizontal line"
+
+[e359820f-bb8b-4eda-8762-47b64dba30a6]
+description = "horizontal line, mines at edges"
+
+[c5198b50-804f-47e9-ae02-c3b42f7ce3ab]
+description = "vertical line"
+
+[0c79a64d-703d-4660-9e90-5adfa5408939]
+description = "vertical line, mines at edges"
+
+[4b098563-b7f3-401c-97c6-79dd1b708f34]
+description = "cross"
+
+[04a260f1-b40a-4e89-839e-8dd8525abe0e]
+description = "large minefield"