题解 | #二叉树遍历#

def ans_post(pre, mid):
    if not pre:
        return ""
    root = pre[0]
    left_mid = mid[: mid.index(root)]
    right_mid = mid[mid.index(root) + 1 :]
    left_pre = pre[1 : len(left_mid) + 1]
    right_pre = pre[len(left_mid) + 1 :]
    left_post = ans_post(left_pre, left_mid)
    right_post = ans_post(right_pre, right_mid)
    return left_post + right_post + root


while True:
    try:
        pre = list(input())
        mid = list(input())
        print(ans_post(pre, mid))
    except:
        break