problem 15 16 18 in julia

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diff --git a/julia/018-maximum_path_sum_i.jl b/julia/018-maximum_path_sum_i.jl
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+###
+# Maximum path sum I
+# Problem 18
+#
+# By starting at the top of the triangle below and moving to adjacent numbers on the row
+# below, the maximum total from top to bottom is 23.
+# 37 4
+# 2 4 6
+# 8 5 9 3
+# That is, 3 + 7 + 4 + 9 = 23.
+# Find the maximum total from top to bottom of the triangle below:
+# 75
+# 95 64
+# 17 47 82
+# 18 35 87 10
+# 20 04 82 47 65
+# 19 01 23 75 03 34
+# 88 02 77 73 07 63 67
+# 99 65 04 28 06 16 70 92
+# 41 41 26 56 83 40 80 70 33
+# 41 48 72 33 47 32 37 16 94 29
+# 53 71 44 65 25 43 91 52 97 51 14
+# 70 11 33 28 77 73 17 78 39 68 17 57
+# 91 71 52 38 17 14 91 43 58 50 27 29 48
+# 63 66 04 68 89 53 67 30 73 16 69 87 40 31
+# 04 62 98 27 23 09 70 98 73 93 38 53 60 04 23
+# NOTE: As there are only 16384 routes, it is possible to solve this problem by trying
+# every route. However, Problem 67, is the same challenge with a triangle containing one-
+# hundred rows; it cannot be solved by brute force, and requires a clever method! ;o)
+###
+
+
+const TRIANGLE = [
+                                [75],
+                              [95, 64],
+                            [17, 47, 82],
+                          [18, 35, 87, 10],
+                        [20, 04, 82, 47, 65],
+                      [19, 01, 23, 75, 03, 34],
+                    [88, 02, 77, 73, 07, 63, 67],
+                  [99, 65, 04, 28, 06, 16, 70, 92],
+                [41, 41, 26, 56, 83, 40, 80, 70, 33],
+              [41, 48, 72, 33, 47, 32, 37, 16, 94, 29],
+            [53, 71, 44, 65, 25, 43, 91, 52, 97, 51, 14],
+          [70, 11, 33, 28, 77, 73, 17, 78, 39, 68, 17, 57],
+        [91, 71, 52, 38, 17, 14, 91, 43, 58, 50, 27, 29, 48],
+      [63, 66, 04, 68, 89, 53, 67, 30, 73, 16, 69, 87, 40, 31],
+    [04, 62, 98, 27, 23, 09, 70, 98, 73, 93, 38, 53, 60, 04, 23],
+]
+
+function triangle_sum(triangle)
+    if length(triangle) == 0
+        return 0
+    end
+    low   = triangle[2:end]
+    left  = map(row -> row[1:end - 1], low)
+    right = map(row -> row[2:end], low)
+    return triangle[1][1] + max(triangle_sum(left), triangle_sum(right))
+end
+
+result = triangle_sum(TRIANGLE)
+
+println(result)