POJ 2752 Seek the Name, Seek the Fame （KMP）

最新推荐文章于 2019-08-13 12:18:36 发布

转载最新推荐文章于 2019-08-13 12:18:36 发布 · 35 阅读

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原文链接：http://www.cnblogs.com/shixinzei/p/7283892.html

本文介绍了一种使用KMP算法找出字符串中既是前缀也是后缀的子串的方法，并提供了一个完整的C++实现示例。通过该算法，可以高效地解决这类字符串匹配问题。

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The little cat is so famous, that many couples tramp over hill and dale to Byteland, and asked the little cat to give names to their newly-born babies. They seek the name, and at the same time seek the fame. In order to escape from such boring job, the innovative little cat works out an easy but fantastic algorithm:

Step1. Connect the father's name and the mother's name, to a new string S.
Step2. Find a proper prefix-suffix string of S (which is not only the prefix, but also the suffix of S).

Example: Father='ala', Mother='la', we have S = 'ala'+'la' = 'alala'. Potential prefix-suffix strings of S are {'a', 'ala', 'alala'}. Given the string S, could you help the little cat to write a program to calculate the length of possible prefix-suffix strings of S? (He might thank you by giving your baby a name:)

Input

The input contains a number of test cases. Each test case occupies a single line that contains the string S described above.

Restrictions: Only lowercase letters may appear in the input. 1 <= Length of S <= 400000.

Output

For each test case, output a single line with integer numbers in increasing order, denoting the possible length of the new baby's name.

Sample Input

ababcababababcabab
aaaaa

Sample Output

2 4 9 18
1 2 3 4 5

给出一个字符串str，求出str中存在多少子串，使得这些子串既是str的前缀，又是str的后缀。从小到大依次输出这些子串的长度。
思路：套KMP模板

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstring>
 4 using namespace std;
 5 const int Max=400005;
 6 char str[Max];
 7 int len,nex[Max],ans[Max];
 8 void getnex()
 9 {
10     int i=0,j=-1;
11     nex[0]=-1;
12     while(i<len){
13         if(j==-1||str[i]==str[j]){
14             i++;
15             j++;
16             nex[i]=j;
17         }
18         else
19             j=nex[j];
20     }
21 }
22 int main()
23 {
24     while(scanf("%s",str)!=EOF){
25         len=strlen(str);
26         getnex();
27         ans[0]=len;
28         int n=0,i=len;
29         while(nex[i]>0){
30             ans[++n]=nex[i];
31             i=nex[i];
32         }
33         for(i=n;i>=0;i--){
34             printf("%d ",ans[i]);
35         }
36         printf("\n");
37     }
38 }

转载于:https://www.cnblogs.com/shixinzei/p/7283892.html