janet/examples/maxtriangle.dst

# Find the maximum path from the top (root)
# of the triangle to the leaves of the triangle.
  
(defn myfold [xs ys]
 (def xs1 (tuple-prepend xs 0))
 (def xs2 (tuple-append xs 0))
 (def m1 (map + xs1 ys))
 (def m2 (map + xs2 ys))
 (map max m1 m2))

(defn maxpath [t]
 (extreme > (reduce myfold () t)))

# Test it
# Maximum path is 3 -> 10 -> 3 -> 9 for a total of 25

(def triangle '[
 [3]
 [7 10]
 [4 3 7]
 [8 9 1 3]
])

(print (maxpath triangle))