你的错误是假设 c [x] == p 和 c [y] == c0 。但索引 x 和 y 派生自 immutable 字符串 s ，它不会反映其洗牌状态下 c 中的值。

Your mistake is assuming c[x] == p and c[y] == c0. But the indexes x and y are derived from the immutable string s, which doesn't reflect the values in c in its shuffled state.