diff --git a/day4/p1improved.nim b/day4/p1improved.nim
new file mode 100644
index 0000000..f7e2431
--- /dev/null
+++ b/day4/p1improved.nim
@@ -0,0 +1,76 @@
+import os
+import std/[strutils, sets, sequtils]
+
+proc didBoardWin(board: var seq[int], size: int, calledNumbers: var HashSet[int]): bool =
+  for i in 0 ..< size:
+    var
+      rowWon = true
+      colWon = true
+
+    let
+      col = i
+      row = i
+
+    for index in 0 ..< size:
+      let
+        rowPos = row*size + index
+        colPos = col + index*size
+
+      rowWon = rowWon and (board[rowPos] in calledNumbers)
+      colWon = colWon and (board[colPos] in calledNumbers)
+
+    if rowWon or colWon:
+      return true
+
+  return false
+
+proc main() =
+  let
+    fileName = paramStr(1)
+    file = open(fileName, fmRead)
+    allNumbers = toSeq(file.readLine().split(",").mapIt(it.parseInt))
+
+  discard file.readLine() # skip blank line
+
+  var boards: seq[seq[int]]
+  boards.add(newSeq[int]())
+
+  var
+    boardIndex = 0
+    boardSize = 0
+
+  while not file.endOfFile():
+    let line = file.readLine()
+
+    if line.strip() == "":
+      boards.add(newSeq[int]())
+      boardIndex += 1
+    else:
+      let board = line.strip().splitWhitespace().mapIt(it.parseInt)
+      boardSize = board.len
+      boards[boardIndex].add(board)
+
+
+  var
+    currentNumbers: HashSet[int]
+    index = 0
+
+  while len(currentNumbers) < len(allNumbers):
+    let num = allNumbers[index]
+
+    currentNumbers.incl(num)
+
+    for board in boards:
+      var board = board
+      if didBoardWin(board, boardSize, currentNumbers):
+        let
+          unmarked = toHashSet(board) - currentNumbers
+          sum = unmarked.toSeq.foldl(a + b)
+        echo "Winner: ", board
+        echo "Score: ", sum*num
+        return
+
+    index += 1
+
+
+main()
diff --git a/day4/p2improved.nim b/day4/p2improved.nim
new file mode 100644
index 0000000..f2a00dd
--- /dev/null
+++ b/day4/p2improved.nim
@@ -0,0 +1,81 @@
+import os
+import std/[strutils, sets, sequtils]
+
+proc didBoardWin(board: var seq[int], size: int, calledNumbers: var HashSet[int]): bool =
+  for i in 0 ..< size:
+    var
+      rowWon = true
+      colWon = true
+
+    let
+      col = i
+      row = i
+
+    for index in 0 ..< size:
+      let
+        rowPos = row*size + index
+        colPos = col + index*size
+
+      rowWon = rowWon and (board[rowPos] in calledNumbers)
+      colWon = colWon and (board[colPos] in calledNumbers)
+
+    if rowWon or colWon:
+      return true
+
+  return false
+
+proc main() =
+  let
+    fileName = paramStr(1)
+    file = open(fileName, fmRead)
+    allNumbers = toSeq(file.readLine().split(",").mapIt(it.parseInt))
+
+  discard file.readLine()
+
+  var boards: seq[seq[int]]
+  boards.add(newSeq[int]())
+
+  var
+    boardIndex = 0
+    boardSize = 0
+
+  while not file.endOfFile():
+    let line = file.readLine()
+
+    if line.strip() == "":
+      # add a new board on newline and increase the board index
+      boards.add(newSeq[int]())
+      boardIndex += 1
+    else:
+      # parse the row and add it to the current board
+      let row = line.strip().splitWhitespace().mapIt(it.parseInt)
+      boardSize = row.len
+      boards[boardIndex].add(row)
+
+  var
+    currentNumbers: HashSet[int]
+    index = 0
+    boardsNotWon = toHashSet(toSeq(0..<boards.len))
+
+  while len(currentNumbers) < len(allNumbers):
+    let num = allNumbers[index]
+
+    currentNumbers.incl(num)
+    var boardsNotWonCopy = boardsNotWon
+    for boardIndex in boardsNotWonCopy:
+      var board = boards[boardIndex]
+      if didBoardWin(board, boardSize, currentNumbers):
+
+        if boardsNotWon.len() == 1: # the last board to win
+          let
+            unmarked = toHashSet(board) - currentNumbers
+            sum = unmarked.toSeq.foldl(a + b)
+          echo "Winner: ", board
+          echo "Score: ", sum*num
+          return
+        boardsNotWon.excl(boardIndex)
+
+    index += 1
+
+
+main()