day 3 ivy solution

day03/sol.ivy

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+) get "input.ivy"
+
+alpha = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ" 
+op vec str = or/ alpha o.== str
+
+# find the first occurence of an element in a vector
+op c index str = +/ and\ c != str
+
+# reshapes a vector as a 1-row matrix
+op lift v = (1, rho v) rho v
+
+op a concat b =
+    0 == rho rho a: b
+    0 == rho rho b: a
+    a, b
+
+nl = "\n"
+null = 0 rho 0
+
+op m parse input =
+    (rho input) == 0: m         # if input is empty return the matrix
+    i = nl index input          # find the first newline
+    k = (i+1) min (rho input)
+    line = i take input         # get chars before the newline
+    rest = k drop input         # get chars after the newline
+    n = (rho line) / 2          # split line into two equal pieces
+    A = vec n take line         # and convert them to 1-hot vectors
+    B = vec n drop line
+    C = (lift A), (lift B)      # make a pair
+    m = m concat lift C         # add the pair to the accumulator matrix
+    m parse rest                # recurse
+
+op parse input = null parse input
+
+op score m = +/ (iota rho alpha) * +/ transp m
+
+op solve m = 
+    score m[;1] and m[;2]
+
+op solve2 m =
+    m = m[;1] or m[;2]
+    n = (rho m)[1] / 3
+    i = -2 + 3 * iota n
+    score m[i] and m[i+1] and m[i+2]
+
+m = parse input
+solve m
+solve2 m