题解 | #小红的数字删除#

import sys
def solve():
    s = sys.stdin.readline().strip()
    cnt = 0
    ans = 0
    for i in s:
        cnt += int(i)
    while True:
        vi, vx = -1, "99"  # 初始化本次删的数位
        if len(s) == 1:
            break
        while len(s) > 0 and s[0] == "0":
            s = s[1:]  # 删除前导零
        for i, v in enumerate(s):
            if (cnt - int(v)) % 3 == 0 and cnt != int(v):
                if v <= vx:  # 考虑删除更靠后的数位
                    vx, vi = v, i
                if vx == "0":
                    break
        if vi == -1:  # 没有合适的数位可删
            break
        else:
            ans += 1
            cnt -= int(vx)  # 更新数位和
            s = s[:vi] + s[vi + 1 :]
    print(ans)


T = int(input())
for _ in range(T):
    solve()

用python纯模拟，能过pypy3，python3过不去