halfprogrammer

(defn find-coll [max-sum acoll]
  (if (empty? acoll)
    [() max-sum]
    (loop [max-sum max-sum
           cur ()
           coll acoll]
      (cond (< max-sum 0) [(list* cur) -1]
            (nil? (seq coll)) [(list* cur) max-sum]
            (and (number? (first coll)) (> (first coll) max-sum)) [(concat () cur) -1]
            (number? (first coll)) (recur (- max-sum (first coll))

halfprogrammer

(defn my-exists1? [lst obj & {:keys [testfn] :or {testfn =}}]
  (when lst
    (if (testfn (first lst) obj)
      lst
      (recur (next lst) obj testfn))))
(my-exists1? '((1 2) (3 4) (5 6)) 3 :testfn #(= (first %1) %2))
=> nil

(defn my-exists2? [lst obj testfn]
  (when lst