a = ["A","B","C","D","E","F","G","H","I","J","K","L","M","N","O","P","Q","R"]
for i in range(10):
    if i == 0 :
       print((''.join(a[i:18])))
       
    if i > 0 :
       print((''.join(a[i::-1]+a[1:18-i])))
       

PHP秒了，这种水题不妨多来一点

ABCDEFGHIJKLMNOPQR
BABCDEFGHIJKLMNOPQ
CBABCDEFGHIJKLMNOP
DCBABCDEFGHIJKLMNO
EDCBABCDEFGHIJKLMN
FEDCBABCDEFGHIJKLM
GFEDCBABCDEFGHIJKL
HGFEDCBABCDEFGHIJK
IHGFEDCBABCDEFGHIJ
JIHGFEDCBABCDEFGHI

for i in range(10):
    first_part = [chr(ord('A') + i - k) for k in range(i+1)]
    second_part = [chr(ord('B') + k) for k in range(17 - i)]
    print(''.join(first_part + second_part))

print(''' ABCDEFGHIJKLMNOPQR BABCDEFGHIJKLMNOPQ CBABCDEFGHIJKLMNOP DCBABCDEFGHIJKLMNO EDCBABCDEFGHIJKLMN FEDCBABCDEFGHIJKLM GFEDCBABCDEFGHIJKL HGFEDCBABCDEFGHIJK IHGFEDCBABCDEFGHIJ JIHGFEDCBABCDEFGHI ''')

print("ABCDEFGHIJKLMNOPQR") print("BABCDEFGHIJKLMNOPQ") print("CBABCDEFGHIJKLMNOP") print("DCBABCDEFGHIJKLMNO") print("EDCBABCDEFGHIJKLMN") print("FEDCBABCDEFGHIJKLM") print("GFEDCBABCDEFGHIJKL") print("HGFEDCBABCDEFGHIJK") print("IHGFEDCBABCDEFGHIJ") print("JIHGFEDCBABCDEFGHI")