weeks 49-52, 263 in Nim

3 files changed, 100 insertions, 0 deletions

diff --git a/challenge-052/archargelod/README b/challenge-052/archargelod/README
new file mode 100644
index 0000000000..6cd57e1074
--- /dev/null
+++ b/challenge-052/archargelod/README
@@ -0,0 +1 @@
+Solution by archargelod
diff --git a/challenge-052/archargelod/nim/ch_1.nim b/challenge-052/archargelod/nim/ch_1.nim
new file mode 100755
index 0000000000..06d42d9975
--- /dev/null
+++ b/challenge-052/archargelod/nim/ch_1.nim
@@ -0,0 +1,16 @@
+#!/usr/bin/env -S nim r -d:release --verbosity:0 --hints:off
+
+proc isStepping*(number: int): bool =
+  let digits = $number
+  for i, c in digits:
+    if i == 0: continue
+    if abs(c.ord - digits[i-1].ord) != 1:
+      return false
+  true
+
+
+when isMainModule:
+  echo "All Stepping Numbers between 100 and 999: "
+  for i in 100..999:
+    if i.isStepping():
+      stdout.write i, ", "
diff --git a/challenge-052/archargelod/nim/ch_2.nim b/challenge-052/archargelod/nim/ch_2.nim
new file mode 100755
index 0000000000..9e5f6f2b26
--- /dev/null
+++ b/challenge-052/archargelod/nim/ch_2.nim
@@ -0,0 +1,83 @@
+#!/usr/bin/env -S nim r -d:release --verbosity:0 --hints:off
+import std/[deques]
+
+type
+  Player = enum
+    P1, P2
+  Game = object
+    piles: Deque[int]
+    turn: Player
+    scores: tuple[p1, p2: int]
+  Node = ref object
+    gameState: Game
+    l, r: Node
+  DecisionTree = object
+    head: Node
+
+proc `$`(n: Node): string =
+  $(n.l.gameState.scores, n.r.gameState.scores)
+
+proc buildTree(node: var Node) =
+  if node.gameState.piles.len == 0:
+    return
+
+  node.l = Node(gameState: node.gameState)
+  node.r = Node(gameState: node.gameState)
+
+  if node.gameState.turn == P1:
+    node.l.gamestate.turn = P2
+    node.r.gamestate.turn = P2
+    node.l.gameState.scores.p1 += node.l.gameState.piles.popFirst()
+    node.r.gameState.scores.p1 += node.r.gameState.piles.popLast()
+  else:
+    node.l.gamestate.turn = P1
+    node.r.gamestate.turn = P1
+    node.l.gameState.scores.p2 += node.l.gameState.piles.popFirst()
+    node.r.gameState.scores.p2 += node.r.gameState.piles.popLast()
+
+  buildTree(node.l)
+  buildTree(node.r)
+
+proc minimax(node: Node, maxiPlayer: bool): int =
+  if node.gameState.piles.len == 0:
+    if node.gameState.scores.p1 > node.gameState.scores.p2:
+      return node.gameState.scores.p1
+    elif node.gameState.scores.p1 < node.gameState.scores.p2:
+      return -1 * node.gameState.scores.p2
+    else:
+      return int(0)
+
+  if maxiPlayer:
+    var bestVal = int.low
+    let val = minimax(node.l, false)
+    let val2 = minimax(node.r, false)
+    bestVal = max(bestVal, max(val, val2))
+    return bestVal
+  else:
+    var bestVal = int.high
+    let val = minimax(node.l, true)
+    let val2 = minimax(node.r, true)
+    bestVal = min(bestVal, min(val, val2))
+    return bestVal
+
+proc maxWinScore*(player: Player, piles: openArray[int]): int =
+  var tree = DecisionTree(
+    head: Node(
+      gamestate: Game(
+        piles: piles.toDeque,
+        turn: P1,
+        scores: (0, 0)
+      )
+    )
+  )
+  buildTree(tree.head)
+  minimax(tree.head, player == P1)
+
+when isMainModule:
+  import std/unittest
+
+  suite "Lucky Winner":
+    test "First player can force win with score 306":
+      let score = P1.maxWinScore([100, 50, 1, 10, 5, 20, 200, 2])
+      check score > 0
+      check score == 306