题解 | 躲藏

import sys
MOD = 2000120420010122
for line in sys.stdin:
    a = line.strip().lower()
    ans = 0
    c = 0
    cw = 0
    cwb = 0
    for x in a:
        if x == 'c':
            ans = (ans+cwb)%MOD
            c += 1
        elif x == 'w':
            cw = (cw+c)%MOD
        elif x == 'b':
            cwb = (cwb+cw)%MOD
    print(ans)

嗨嗨嗨，代码过程如上，a代表输入字符串，x代表字母，然后c, cw, cwb 分别代表字符串"c", "cw", "cwb"字符串个数，ans则是cwbc个数，然后记得模模数，以防溢出