hdu 3793 浙大计算机研究生保研复试上机考试-2011年

Is It Symmetric

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 391    Accepted Submission(s): 159

Problem Description

It is easy to see that a string of digits like 1234321 is symmetric with 4 being the central digit. However it is less obvious if we consider the string as a circular one and shift it to the left as 2343211. Your task is to write a program to check if a circular string is symmetric.

 

Input

Your program must read test cases from standard input.
The input file consists of several test cases. Each case occupies a line which contains the string. Each string contains less than 100 digits.
The input is finished by a "#".

 

Output

For each test case, your program must output to standard output. If the string is not symmetric, output "NO" in a line; else output "YES", followed by a space and the position of the center (the position index starts from 0). It is guaranteed that the length of the string is an odd number and the center is unique.

 

Sample Input

   
   
   
   

    
    
    
    2112343
798
#
   
   
   
   

 

Sample Output

   
   
   
   

    
    
    
    YES 5
NO
   
   
   
   

 

Source

浙大计算机研究生保研复试上机考试-2011年

#include "iostream"
#include "stdio.h"
#include "math.h"
#include "vector"
#include "queue"
#include "memory.h"
#include "algorithm"
#include "string"
using namespace std;
#define N 105
char str[N];

int Div(int s,int t)
{
    int center=-2;
    if(s==t)
       center=-1;
    bool flag=(t-s+1)%2;
    while(t>s&&str[s]==str[t])
        s++,t--;
    if(s>t&&!flag)//even
        center=-1;
    else if(s==t&&flag)//odd
        center=s;
    return center;
}

int main()
{
    int center1,center2,center;
    while(cin>>str&&strcmp(str,"#")!=0)
    {
        int len=strlen(str);
        bool flag=false;
        for(int i=0;i<len;i++)
        {
            center1=Div(0,i);
            center2=Div(i+1,len-1);
            if(center1!=-2&&center2!=-2)
            {
                center=center1==-1?center2:center1;
                cout<<"YES "<<center<<endl;
                flag=true;
                break;
            }
        }
        if(!flag)
            printf("NO\n");
    }
}