PAT 1040 Longest Symmetric String

#include <cstdio>

#include <cstdlib>



using namespace std;



char line[1001];

char line2[2003];



int syslen(char str[], int start) {

    int len = 1;

    int p = start - 1;

    int q = start + 1;

    while (p >=0 && str[q] != '\0' && str[p] == str[q]) {

        p--, q++;

        len += 2;

    }

    return len;

}



int main() {

    scanf("%[^\n]s", line);

    

    int p = 0, q = 0;

    line2[p++] = ' ';

    line2[p++] = line[q++];

    while (line[q] != '\0') {

        line2[p++] = ' '; // dummy char used as seperator

        line2[p++] = line[q++];

    }

    line2[p++] = ' ';

    line2[p] = '\0';

    int max_len = 0;

    for (int i=0; i<p; i++) {

        int cur_len = syslen(line2, i);

        if (cur_len > max_len) max_len = cur_len;

    }

    printf("%d", max_len/2);

    return 0;

}

brute force for small case