POJ 2752 Seek the Name, Seek the Fame

Seek the Name, Seek the Fame

Time Limit: 2000MS		Memory Limit: 65536K
Total Submissions: 14875		Accepted: 7471

Description

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

這個題目問的是保證前綴和後綴相同的情況下，求解這個前綴或後綴的長度。

KMP的next值不就是該位前面的字符串中前綴後綴長度相同的位數麼。

我們只需要從最後面第len(len爲字符串長度)開始找，找到一個前綴和後綴長度後，跳到前綴的後一個，繼續把前綴作爲處理的字符串繼續找。直到最後到0.代碼如下：

/*************************************************************************
	> File Name: Seek_the_Name.cpp
	> Author: Zhanghaoran
	> Mail: [email protected]
	> Created Time: Thu 26 Nov 2015 05:00:27 PM CST
 ************************************************************************/

#include <iostream>
#include <algorithm>
#include <cstring>
#include <cstdio>
#include <cstdlib>

using namespace std;

void prekmp(char x[], int m, int nextKmp[]){
    int i, j;
    i = 0;
    j = nextKmp[0] = -1;
    while(i < m){
        if(j == -1 || x[i] == x[j])
            nextKmp[++ i] = ++ j;
        else 
            j = nextKmp[j];
    }
    //for(int i = 0; i <= m; i ++)
    //    cout << nextKmp[i] << " ";
    //cout << endl;
}

int nexti[1000010];
char a[1000010];
int temp[1000010];
int main(void){
    while(~scanf("%s", a)){
        int ans = 0;
        int len = strlen(a);
        prekmp(a, len, nexti);
        int p = len;
        temp[ans ++] = len;
        while(nexti[p]){
            p = nexti[p];
            temp[ans ++] = p;
        }
        for(int i = ans - 1; i >= 0; i --)
            cout << temp[i] << " ";
        cout << endl;
    }
}