zoukankan      html  css  js  c++  java
  • Power Strings(求循环次数最多的循环节 kmp)

    Given two strings a and b we define a*b to be their concatenation. For example, if a = "abc" and b = "def" then a*b = "abcdef". If we think of concatenation as multiplication, exponentiation by a non-negative integer is defined in the normal way: a^0 = "" (the empty string) and a^(n+1) = a*(a^n).

    Input

    Each test case is a line of input representing s, a string of printable characters. The length of s will be at least 1 and will not exceed 1 million characters. A line containing a period follows the last test case.

    Output

    For each s you should print the largest n such that s = a^n for some string a.

    Sample Input

    abcd
    aaaa
    ababab
    .
    

    Sample Output

    1
    4
    3
    

    Hint

    This problem has huge input, use scanf instead of cin to avoid time limit exceed.

    nxt数组典型应用求循环节

    对于长度n 循环节次数就是n/(n-nxt[n]) 很容易推导

    #include<cstdio>
    #include<string.h>
    using namespace std;
    char s[400005];
    int nxt[400005];
    int n;
    void get_nxt()
    {
        int i=0;
        int k=-1;
        nxt[0]=-1;
        while(i<n)
        {
            if(k==-1||s[i]==s[k])
            {
                i++;
                k++;
                nxt[i]=k;
            }
            else
            {
                k=nxt[k];
            }
        }
        return;
    }
    int ans[400005];
    int main()
    {
        while(~scanf("%s",s))
        {
            n=strlen(s);
            get_nxt();
            int cnt=0;
            ans[++cnt]=n;
            int x=n;
            while(x)
            {
                x=nxt[x];
                if(x!=0)
                {
                    ans[++cnt]=x;
                }
            }
            for(int i=cnt;i>=1;i--)
            {
                printf("%d%s",ans[i],i==1?"
    ":" ");
            }
        }
        return 0;
    }
    
  • 相关阅读:
    SQL 联合语句
    Strust2MVC
    struts2执行流程
    struts2的验证框架
    poj 1201 Intervals
    FZOJ Problem 2219 StarCraft
    poj 3470 Walls
    hdu 6021 MG loves string
    FZOJ Problem 2150 Fire Game
    FZOJ Problem 2148 Moon Game
  • 原文地址:https://www.cnblogs.com/caowenbo/p/11852214.html
Copyright © 2011-2022 走看看