IDDFS 加法链

An addition chain for n is an integer sequence with the following four properties: • a0 = 1 • am = n • a0 < a1 < a2 < · · · < am−1 < am • For each k (1 ≤ k ≤ m) there exist two (not neccessarily different) integers i and j (0 ≤ i, j ≤ k−1) with ak = ai + aj You are given an integer n. Your job is t