題目：

題解：

func isIsomorphic(s, t string) bool {s2t := map[byte]byte{}t2s := map[byte]byte{}for i := range s {x, y := s[i], t[i]if s2t[x] > 0 && s2t[x] != y || t2s[y] > 0 && t2s[y] != x {return false}s2t[x] = yt2s[y] = x}return true
}