June 2018 Update

Task/Solve-a-Hidato-puzzle/Kotlin/solve-a-hidato-puzzle.kotlin

@@ -0,0 +1,75 @@
+// version 1.2.0
+
+lateinit var board: List<IntArray>
+lateinit var given: IntArray
+lateinit var start: IntArray
+
+fun setUp(input: List<String>) {
+    val nRows = input.size
+    val puzzle = List(nRows) { input[it].split(" ") }
+    val nCols = puzzle[0].size
+    val list = mutableListOf<Int>()
+    board = List(nRows + 2) { IntArray(nCols + 2) { -1 } }
+    for (r in 0 until nRows) {
+        val row = puzzle[r]
+        for (c in 0 until nCols) {
+            val cell = row[c]
+            if (cell == "_") {
+                board[r + 1][c + 1] = 0
+            }
+            else if (cell != ".") {
+                val value = cell.toInt()
+                board[r + 1][c + 1] = value
+                list.add(value)
+                if (value == 1) start = intArrayOf(r + 1, c + 1)
+            }
+        }
+    }
+    list.sort()
+    given = list.toIntArray()
+}
+
+fun solve(r: Int, c: Int, n: Int, next: Int): Boolean {
+    if (n > given[given.lastIndex]) return true
+    val back = board[r][c]
+    if (back != 0 && back != n) return false
+    if (back == 0 && given[next] == n) return false
+    var next2 = next
+    if (back == n) next2++
+    board[r][c] = n
+    for (i in -1..1)
+        for (j in -1..1)
+            if (solve(r + i, c + j, n + 1, next2)) return true
+    board[r][c] = back
+    return false
+}
+
+fun printBoard() {
+    for (row in board) {
+        for (c in row) {
+            if (c == -1)
+                print(" . ")
+            else
+                print(if (c > 0) "%2d ".format(c) else "__ ")
+        }
+        println()
+    }
+}
+
+fun main(args: Array<String>) {
+    var input = listOf(
+        "_ 33 35 _ _ . . .",
+        "_ _ 24 22 _ . . .",
+        "_ _ _ 21 _ _ . .",
+        "_ 26 _ 13 40 11 . .",
+        "27 _ _ _ 9 _ 1 .",
+        ". . _ _ 18 _ _ .",
+        ". . . . _ 7 _ _",
+        ". . . . . . 5 _"
+    )
+    setUp(input)
+    printBoard()
+    println("\nFound:")
+    solve(start[0], start[1], 1, 0)
+    printBoard()
+}

Task/Solve-a-Hidato-puzzle/Perl-6/solve-a-hidato-puzzle.pl6

@@ -57,7 +57,7 @@ sub solveboard($board) {
 
         my $old = @grid[$y][$x];
 
-        return False if $old and $old != $v;
+        return False if +$old and $old != $v;
         return False if @known[$v] and @known[$v] !eqv $coord;
 
         @grid[$y][$x] = $v;               # conjecture grid value