4clojure 题解 Interleave Two Seqs

交织两个序列，不得使用interleave操作

Write a function which takes two sequences and returns the first item from each, then the second item from each, then the third, etc.

	(= (__ [1 2 3] [:a :b :c]) '(1 :a 2 :b 3 :c))
	(= (__ [1 2] [3 4 5 6]) '(1 3 2 4))
	(= (__ [1 2 3 4] [5]) [1 5])
	(= (__ [30 20] [25 15]) [30 25 20 15])

用loop循环搞定

(loop [s1 a
       s2 b
       ret (empty a)]
  (if (or (empty? s1) 
          (empty? s2))
    ret
    (recur (rest s1)
           (rest s2)
            (conj ret 
                  (first s1)
                  (first s2)) )))

看到github上有个比较巧妙的方式

mapcat vector

(mapcat vector [1 2 3] [:a :b :c])
=> (1 :a 2 :b 3 :c)