Solution to 1244B of the codeforces problemset

1244B.c

    #include <stdio.h>
     
    int main()
    {
        int t, n, max, i;
        scanf("%d",&t); // test cases
        while(t--)
        {
            scanf("%d",&n); // n=number of rooms
            char s[n+1];
            max=0;
            scanf("%s",s); //arrays
     
            for(i=0;s[i]!='\0';i++)
                if(s[i]=='1') //if there's a staircase
                {
                    if(i+1>max) max=i+1; //from which side, the steps are max
                    if(n-i>max) max=n-i;
                }
            printf("%d\n",max?2*max:n); //print
        }
    }