problem 099 haskell, wip 058

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diff --git a/haskell/099-largest_exponential.hs b/haskell/099-largest_exponential.hs
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+------
+-- Largest exponential
+-- Problem 99
+--
+-- Comparing two numbers written in index form like 211 and 37 is not difficult,
+-- as any calculator would confirm that 211 = 2048 < 37 = 2187.
+-- However, confirming that 632382518061 > 519432525806 would be much more difficult,
+-- as both numbers contain over three million digits.
+-- Using base_exp.txt (right click and 'Save Link/Target As...'), a 22K text file
+-- containing one thousand lines with a base/exponent pair on each line, determine which
+-- line number has the greatest numerical value.
+-- NOTE: The first two lines in the file represent the numbers in the example given above.
+------
+
+
+import Data.List(elemIndex, maximumBy)
+import Data.Maybe(fromJust)
+
+main = do
+    content <- readFile "../data/099_base_exp.txt"
+    let base_exp = map (map (\s -> read s :: Integer) . split ',') $ lines content
+    print (fst $ maximumBy (\(i, be1) (j, be2) -> compare be1 be2)
+            $ map (\(i, be) -> (i, head be ^ last be)) $ zip [1..] base_exp)
+
+split :: Eq a => a -> [a] -> [[a]]
+split _ [] = [[]]
+split delim str =
+    let (before, remainder) = span (/= delim) str
+    in  before : case remainder of [] -> []
+                                   x  -> split delim $ tail x