7-10 longest symmetric substring (25 points) (violence problem solution) C language

For a given string , This problem requires you to output the length of the longest symmetric substring . for example , Given Is PAT&TAP symmetric?, The longest symmetric substring is s PAT&TAP s, So you should output 11.

Input format ：

The input is given on a line, and the length is no more than 1000 Non empty string for .

Output format ：

Output the length of the longest symmetric substring in one line .

sample input ：

Is PAT&TAP symmetric?

No blank lines at the end

sample output ：

11

No blank lines at the end

  Ideas ： End of string j=strlen(s)-1 Go ahead and find the front i=0 Same character , Then judge the previous character and the matching character interval

j-i+1 Whether the characters in the meet the palindrome , If meet , Then replace max The value is the interval value j-i+1. If not, then j Look forward to , After finding one side ,i++ Continue with the previous operation

#include<stdio.h>
#include<string.h>
int main()
{
    char s[1002];
    gets(s);
    int max=1;
    for(int i=0;i<strlen(s);i++)
    {
        for(int j=strlen(s)-1;j>=0;j--)
        {
            int left=i,right=j;
            while(left<=right&&s[left++]==s[right--])// Traverse left~right Internal elements 
            {
                if(left>right)// When left~right The condition is executed after traversing all elements in the scope 
                {
                    if(max<j-i+1)
                    {
                        max=j-i+1;
                    }
                }
                    
            }
        }
    }
    printf("%d",max);
    return 0;
}