题解 | #密码截取#

package main

import (
	"bufio"
	"fmt"
	"os"
	"sort"
)

func main() {
	in := bufio.NewScanner(os.Stdin)
	in.Scan()
	str := in.Text()
	var ret []int
	for i := 0; i < len(str); i++ {
		aba := valid(str, i, i)
		abba := valid(str, i, i+1)
		ret = append(ret, aba, abba)
	}
	sort.Ints(ret)
	fmt.Println(ret[len(ret)-1])
}

func valid(s string, i, j int) int {
	for i >= 0 && j <= len(s)-1 && s[i] == s[j] {
		i--
		j++
	}

	return j - i - 1
}