package main

func longestPalindrome(s string) string {
	ll := len(s)
	if ll == 0 {
		return ""
	}

	var l, r, pl, pr int

	for r < ll {
		for r+1 < ll && s[l] == s[r+1] {
			r++
		}
		for l-1 >= 0 && r+1 < ll && s[l-l] == s[r+1] {
			l--
			r++
		}
		if r-l > pr-pl {
			pl, pr = l, r
		}
		l = (l+r) / 2 + 1
		r = l
	}
	return s[pl:pr+1]
}


func Min(i,j int) int {
	if i < j {
		return i
	} else {
		return j
	}
}

func isPalindrome(s string) bool {
	if len(s) < 2 {
		return true
	}
	for i := range s {
		if len(s)-1 -i >= i {
			if s[i] != s[len(s)-i-1] {
				return false
			}
		}
	}
	return true
}

func longestPalindrome2(s string) string {
	max_length := 0
	max_str := ""

	str := ""
	length := 0

	for i := range s {
		length = Min(i, len(s)-1-i)
		for idx:= 0; idx < length; idx++ {
			str = s[i-idx:i+idx+1]
			if isPalindrome(str) {
				if len(str) > max_length {
					max_length = len(str)
					max_str = str
				}
			}
		}
	}
	return max_str
}