455:Periodic Strings

A character string is said to have period k if it can be formed by concatenating one or more repetitionsof another string of length k. For example, the string ”abcabcabcabc” has period 3, since it is formedby 4 repetitions of the string ”abc”. It also has periods 6 (two repetitions of ”abcabc”) and 12 (onerepetition 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 yourprogram will test followed by a blank line. Each test case will contain a single character string of upto 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 areseparated by a blank line.

Sample Input

1

HoHoHo

Sample Output

2

开始的代码如下没过,原因是我判断 i 是否是字符串周期的时候并没有事先判断字符串长度是否能被 i 整除:

#include<cstdio>
#include<cstring>
#define maxn 80 + 5
char s[maxn];
int main(){
    int T;
    scanf("%d",&T);
    while(T--){
        scanf("%s",s);
        int n = strlen(s),i;
        for(i = 1;i <= n/2;i++){
            int mark = 1;
            for(int k = 0;k < i;k++){
                for(int j = i + k;j < n;j += i){
                    if(s[j] != s[j-i]) mark = 0;
                }
            }
            if(mark){
                printf("%d\n",i);
                break;
            }
        }
        if(i > n/2) printf("%d\n",n);
    }

    return 0;
}

修改之后的代码:

#include<cstdio>
#include<cstring>
#define maxn 80 + 5
char s[maxn];
int main(){
    int T;
    scanf("%d",&T);
    while(T--){
        scanf("%s",s);
        int n = strlen(s),i;
        for(i = 1;i <= n/2;i++){
            if(!(n%i)){
                int mark = 1;
                for(int k = 0;k < i;k++){
                    for(int j = i + k;j < n;j += i){
                        if(s[j] != s[j-i]) mark = 0;
                    }
                }
                if(mark){
                    printf("%d\n",i);
                    break;
                }
            }
        }
        if(i > n/2) printf("%d\n",n);
        if(T) putchar('\n');
    }

    return 0;
}

参考别人的代码:

#include<cstdio>
#include<cstring>
#define maxn 80 + 5
char s[maxn];
int main(){
    int T;
    scanf("%d",&T);
    while(T--){
        scanf("%s",s);
        int len = strlen(s),i,k;
        for(i = 1;i <= len;i++){
            if(!(len % i)){
                //判断是否是周期串直接对 i 求余即可,比我之前的好多了
                for(k = 0;k < len;k++){
                    if(s[k] != s[k % i]) break;
                }
                if(k == len){
                    printf("%d\n",i);
                    break;
                }
            }
        }
        if(T) putchar('\n');
    }

    return 0;
}

posted @ 2018-04-05 00:20  ACLJW  阅读(255)  评论(0编辑  收藏  举报