hdu 3374 String Problem (字符串最小最大表示 + KMP求循环节)

Problem - 3374

 

KMP求循环节。

http://www.cnblogs.com/wuyiqi/archive/2012/01/06/2314078.html

 

　　循环节推导的证明相当的好，这题是很裸的套算法的题。

代码如下：

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

 using namespace std;

 const int N = ;
 char buf[N];
 int next[N];

 void getNext(char *str) {
     char *si = str;
     int *ni = next;
     int j = *next = -;
     while (*si) {
         while (j > - && *si != *(str + j)) j = *(next + j);
         si++, ni++, j++;
 //        if (*si == *(str + j)) *ni = *(next + j);
 //        else *ni = j;
         *ni = j;
     }
 }

 int minMaxExp(char *s, bool mini) {
     int i = , j = , k = , t;
     int len = strlen(s);
     while (i < len && j < len && k < len) {
 //        cout << i << ' ' << j << ' ' << k << endl;
         t = s[(i + k) % len] - s[(j + k) % len];
         if (!t) k++;
         else {
             if (mini ^ (t > )) j += k + ;
             else i += k + ;
             if (i == j) j++;
             k = ;
         }
     }
     return min(i, j);
 }

 int main() {
     while (cin >> buf) {
         getNext(buf);
 //        for (int i = 0, sz = strlen(buf); i < sz; i++) cout << next[i] + 1 << ' '; cout << endl;
         int cycle = strlen(buf);
 //        cout << "got next" << endl;
         cycle /= (cycle - next[cycle - ] - );
         cout << minMaxExp(buf, true) +  << ' ' << cycle << ' ' << minMaxExp(buf, false) +  << ' ' << cycle << endl;
     }
     return ;
 }

 

——written by Lyon