求最小循環節長度UVA - 455

A character string is said to have period k if it can be formed by concatenating one or more repetitions
of another string of length k. For example, the string ”abcabcabcabc” has period 3, since it is formed
by 4 repetitions of the string ”abc”. It also has periods 6 (two repetitions of ”abcabc”) and 12 (one
repetition of ”abcabcabcabc”).
Write a program to read a character string and determine its smallest period.

Input

The first line oif the input file will contain a single integer N indicating how many test case that your
program will test followed by a blank line. Each test case will contain a single character string of up
to 80 non-blank characters. Two consecutive input will separated by a blank line.

Output

An integer denoting the smallest period of the input string for each input. Two consecutive output are
separated by a blank line.

Sample Input

1

HoHoHo

Sample Output

2

思路: 暴力枚舉循環節長度，循環問題用求模運算

//#define LOCAL/*注意提交時將此行代碼註釋掉*/
//#include<windows.h>
#include<iostream>
#include<cstdio>
#include<cstring>
#include<cmath>
using namespace std;
int fun(char *str)
{
    int k,len=strlen(str);
    for(int i=1;i<=strlen(str);i++)
    {//i是循序節長度
        int flag=1;

        if(len%i==0)
        {
            for(k=i;k<len;k++)
               {
                   if(str[k]!=str[k%i])//循環用求模運算   使得後面的字符與最初的循環體進行比較
                   {
                       flag=0;
                       break;
                   }
               }
               if(flag)
                    return i;
        }
    }
    return len;
}
int main()
{
//讀寫文件代碼寫在這裏不會影響計時函數
#ifdef LOCAL
    freopen( "input.txt", "r", stdin );
    freopen( "output.txt", "w", stdout );
#endif // LOCAL

    /*計時函數*/
#ifdef LOCAL
    DWORD start_time, end_time;
    start_time = GetTickCount();
#endif // LOCAL
/*main函數主體*/

    int N;
    int flag=0;
    cin >> N;
    //getchar();
    char str[100];
    while(N--)
    {
        cin >> str;
        cout << fun(str) << endl;
        if(N)
            cout<<endl;

    }


#ifdef LOCAL
    end_time = GetTickCount();
//提交時將時間函數輸出註釋掉
    cout << "Running time is: " << static_cast<double>( end_time - start_time ) * 1.0 / 1000 << "ms" << endl; //輸出運行時間
#endif // LOCAL
    return 0;
}