Initial commit

4.jl

@@ -0,0 +1,83 @@
+include("utils.jl")
+
+function parse_boards(lines)
+    num_boards = div(length(lines),5)
+    boards = Array{Array{Int}}(undef, num_boards)
+    for i in 1:num_boards
+        boards[i] = zeros(5, 5)
+        for li in 1:5
+            values = map(x->parse(Int, x), split(lines[(i - 1)*5+li]))
+            boards[i][li,:] .= values
+        end
+    end
+    boards
+end
+
+function parse_input(filename)
+    lines = Iterators.Stateful(non_empty_lines(filename))
+    numbers = map(x->parse(Int, x), split(popfirst!(lines), ","))
+    boards = parse_boards(collect(lines))
+    numbers, boards
+end
+
+function apply(number, boards)
+    for board in boards
+        for i in CartesianIndices((1:5, 1:5))
+            if board[i] == number
+                board[i] = -1
+            end
+        end
+    end
+end
+
+function check(boards)
+    for board in boards
+        for i in 1:5
+            if (reduce(+, board[i,:]) == -5) || (reduce(+, board[:,i]) == -5)
+                return true, board
+            end
+        end
+    end
+    false, nothing
+end
+
+function solution4_1()
+    numbers, boards = parse_input("4.data")
+    for number in numbers
+        apply(number, boards)
+        winning, board = check(boards)
+        if winning
+            score = reduce(+, filter(>(0), board))
+            return (score, number, score * number)
+        end
+    end
+end
+
+function remove_winning_boards(boards)
+    last = nothing
+    filtered = filter(boards) do board
+        for i in 1:5
+            if (reduce(+, board[i,:]) == -5) || (reduce(+, board[:,i]) == -5)
+                last = board
+                return false
+            end
+        end
+        true
+    end
+    filtered, last
+end
+
+
+function solution4_2()
+    numbers, boards = parse_input("4.data")
+    for number in numbers
+        apply(number, boards)
+        boards, board = remove_winning_boards(boards)
+        if length(boards) == 0
+            score = reduce(+, filter(>(0), board))
+            return (score, number, score * number)
+        end
+    end
+end
+
+solution4_2()