LeetCode题解(Golang实现)--Longest Palindromic Substring

题目

Given a string s, find the longest palindromic substring in s. You may assume that the maximum length of s is 1000.

Example:

Input: "babad"

Output: "bab"

Note: "aba" is also a valid answer.
Example:

Input: "cbbd"

Output: "bb"

解题思路

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答案

package main
import "fmt"

func main() {
    fmt.Println(longestPalindrome(""))
}

func longestPalindrome(s string) string {
    start, end := 0, 0
    for i := 0; i < len(s); i = i + 1 {
        len1 := expandAroundCenter(s, i, i)
        len2 := expandAroundCenter(s, i, i+1)
        len := len1
        if len2 > len1 {
            len = len2
        }
        if len > end-start {
            start = i - (len-1)/2
            end = i + len/2
        }
    }
    return s[start : end+1]
}

func expandAroundCenter(s string, left int, right int) int {
    L, R := left, right
    for L >= 0 && R < len(s) && s[L] == s[R] {
        L = L - 1
        R = R + 1
    }
    return R - L - 1
}