KMP POJ 2406 Power Strings

 1 /*
 2     题意：一个串有字串重复n次产生，求最大的n
 3     KMP：nex[]的性质应用，感觉对nex加深了理解
 4 */
 5 /************************************************
 6 * Author        :Running_Time
 7 * Created Time  :2015-8-10 10:51:54
 8 * File Name     :POJ_2406.cpp
 9  ************************************************/
10 
11 #include <cstdio>
12 #include <algorithm>
13 #include <iostream>
14 #include <sstream>
15 #include <cstring>
16 #include <cmath>
17 #include <string>
18 #include <vector>
19 #include <queue>
20 #include <deque>
21 #include <stack>
22 #include <list>
23 #include <map>
24 #include <set>
25 #include <bitset>
26 #include <cstdlib>
27 #include <ctime>
28 using namespace std;
29 
30 #define lson l, mid, rt << 1
31 #define rson mid + 1, r, rt << 1 | 1
32 typedef long long ll;
33 const int MAXN = 1e6 + 10;
34 const int INF = 0x3f3f3f3f;
35 const int MOD = 1e9 + 7;
36 char str[MAXN];
37 int nex[MAXN];
38 
39 int get_nex(void)   {
40     int len = strlen (str);
41     int i = 0, j = -1;  nex[0] = -1;
42     while (i < len) {
43         if (j == -1 || str[j] == str[i])    {
44             j++;    i++;    nex[i] = j;
45         }
46         else    j = nex[j];
47     }
48     if (i % (i - nex[i]) == 0)  {
49         return i / (i - nex[i]);
50     }
51     else    return 1;
52 }
53 
54 int main(void)    {     //POJ 2406 Power Strings
55     while (scanf ("%s", str) == 1)  {
56         if (str[0] == '.')  break;
57         printf ("%d
", get_nex ());
58     }
59 
60     return 0;
61 }
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