Contest3182 - the 39th individual training match for 2021 freshmen_ F: ss

 

 

// There exists a non-empty even string 
// that can be obtained by deleting one or more characters from the end of S.

//
#include<bits/stdc++.h>
using namespace std;

const int MAXN=222;
char str[MAXN];

bool judge( int len )
{
    if( len&1 ) return false;

    char *p1=str;
    char *p2=str+len/2;
    int cnt=0;

    while( cnt<len/2 )
    {
        if( *p1!=*p2 ) return false;
        p1++; p2++; cnt++;
    }
    return true;
}

int main()
{
    while( ~scanf("%s",str) )
    {
        int len=strlen(str);          // -1 
        while( judge( --len )==false );
        printf("%d\n",len);
    }
    return 0;
}

//
find:
01 len/2  Be careful   Discrimination between subscript and quantity  -1
02  Pay attention to the meaning of the question   Original string does not count   At least one character must be subtracted