题目：

题解：

func shortestPalindrome(s string) string {n := len(s)fail := make([]int, n)for i := 0; i < n; i++ {fail[i] = -1}for i := 1; i < n; i++ {j := fail[i - 1]for j != -1 && s[j + 1] != s[i] {j = fail[j]}if s[j + 1] == s[i] {fail[i] = j + 1}}best := -1for i := n - 1; i >= 0; i-- {for best != -1 && s[best + 1] != s[i] {best = fail[best]}if s[best + 1] == s[i] {best++}}add := ""if best != n - 1 {add = s[best + 1:]}b := []byte(add)for i := 0; i < len(b) / 2; i++ {b[i], b[len(b) - 1 -i] = b[len(b) - 1 -i], b[i]}return string(b) + s
}