Rabin_Karp(hash) HDOJ 1711 Number Sequence

题目传送门

 /*
 　　Rabin_Karp：虽说用KMP更好，但是RK算法好理解。简单说一下RK算法的原理：首先把模式串的哈希值算出来，
         在文本串里不断更新模式串的长度的哈希值，若相等，则找到了，否则整个模式串的长度的哈希值向右移动一位
 */
 /************************************************
 * Author        :Running_Time
 * Created Time  :2015-8-5 14:04:26
 * File Name     :HDOJ_1711.cpp
  ************************************************/

 #include <cstdio>
 #include <algorithm>
 #include <iostream>
 #include <sstream>
 #include <cstring>
 #include <cmath>
 #include <string>
 #include <vector>
 #include <queue>
 #include <deque>
 #include <stack>
 #include <list>
 #include <map>
 #include <set>
 #include <bitset>
 #include <cstdlib>
 #include <ctime>
 using namespace std;

 #define lson l, mid, rt << 1
 #define rson mid + 1, r, rt << 1 | 1
 typedef unsigned long long ull;
 typedef long long ll;
 const int MAXN = 1e6 + ;
 const int MAXM = 1e4 + ;
 const int INF = 0x3f3f3f3f;
 const ull KEY = ;
 int a[MAXN], b[MAXM];
 int n, m;

 int match(void) {
     ull h = ;
     for (int i=; i<m; ++i)    h *= KEY;
     ull ah = , bh = ;
     for (int i=; i<m; ++i)    ah = ah * KEY + a[i];
     for (int i=; i<m; ++i)    bh = bh * KEY + b[i];
     for (int i=; i+m<=n; ++i)    {
         if (ah == bh)   return i + ;
         if (i + m < n) {
             ah = ah * KEY + a[i+m] - a[i] * h;
         }
     }
     return -;
 }

 int main(void)    {     //HDOJ 1711 Number Sequence
     int T;  scanf ("%d", &T);
     while (T--) {
         scanf ("%d%d", &n, &m);
         for (int i=; i<n; ++i)    scanf ("%d", &a[i]);
         for (int i=; i<m; ++i)    scanf ("%d", &b[i]);
         printf ("%d\n", match ());
     }

     return ;
 }

 /*
     题目链接：http://oj.acm.zstu.edu.cn/JudgeOnline/problem.php?id=4194
     给你两个字符串A，B，请输出B字符串在A字符串中出现了几次。
 */
 /************************************************
  * Author        :Running_Time
  * Created Time  :2015-8-5 14:04:26
  * File Name     :ZSTU 4194 字符串匹配
  ************************************************/

 #include <cstdio>
 #include <algorithm>
 #include <iostream>
 #include <sstream>
 #include <cstring>
 #include <cmath>
 #include <string>
 #include <vector>
 #include <queue>
 #include <deque>
 #include <stack>
 #include <list>
 #include <map>
 #include <set>
 #include <bitset>
 #include <cstdlib>
 #include <ctime>
 using namespace std;

 #define lson l, mid, rt << 1
 #define rson mid + 1, r, rt << 1 | 1
 typedef unsigned long long ull;
 typedef long long ll;
 const int MAXN = 1e6 + ;
 const int INF = 0x3f3f3f3f;
 const ull KEY = ;
 char t[MAXN], p[MAXN];

 int Rabin_Karp(void) {
     int lent = strlen (t);
     int lenp = strlen (p);
     ull h = ;
     for (int i=; i<lenp; ++i)    h *= KEY;
     ull th = , ph = ; int ret = ;
     for (int i=; i<lenp; ++i)    th = th * KEY + t[i];
     for (int i=; i<lenp; ++i)    ph = ph * KEY + p[i];
     for (int i=; i+lenp<=lent; ++i)    {
         if (th == ph)   {
             ret++;
             for (int j=i; j<=i+lenp-; ++j) {       //找到了一个模式串，不能再用，整个跳过去
                 th = th * KEY + t[j+lenp] - t[j] * h;
             }
             i += lenp - ;  continue;
         }
         if (i + lenp < lent) {
             th = th * KEY + t[i+lenp] - t[i] * h;
         }
     }
     return ret;
 }

 int main(void)    {     //ZSTU 4194 字符串匹配
     while (scanf ("%s %s", t, p) == )  {
         printf ("%d\n", Rabin_Karp ());
     }

     return ;
 }

Rabin_Karp应用

 /*
     这就是赤裸裸的模板题，只不过用数字而已
 */
 /************************************************
 * Author        :Running_Time
 * Created Time  :2015-8-9 19:45:40
 * File Name     :KMP.cpp
  ************************************************/

 #include <cstdio>
 #include <algorithm>
 #include <iostream>
 #include <sstream>
 #include <cstring>
 #include <cmath>
 #include <string>
 #include <vector>
 #include <queue>
 #include <deque>
 #include <stack>
 #include <list>
 #include <map>
 #include <set>
 #include <bitset>
 #include <cstdlib>
 #include <ctime>
 using namespace std;

 #define lson l, mid, rt << 1
 #define rson mid + 1, r, rt << 1 | 1
 typedef long long ll;
 const int MAXN = 1e6 + ;
 const int INF = 0x3f3f3f3f;
 const int MOD = 1e9 + ;
 int nex[MAXN];
 int s[MAXN], t[MAXN];

 void get_nex(int lm)    {
     int i = , j = -;   nex[] = -;
     while (i < lm)  {
         if (j == - || t[j] == t[i]) {
             i++;    j++;    nex[i] = j;
         }
         else    j = nex[j];
     }
 }

 int KMP(int ln, int lm)   {
     get_nex (lm);
     int i = , j = ;
     while (i < ln)  {
         while (j != - && s[i] != t[j]) j = nex[j];
         i++;    j++;
         if (j == lm) return (i - j + );
     }
     return -;
 }

 int main(void)    {     //HDOJ 1711 Number Sequence
     int T;  scanf ("%d", &T);
     while (T--)   {
         int ln, lm; scanf ("%d%d", &ln, &lm);
         for (int i=; i<ln; ++i)   scanf ("%d", &s[i]);
         for (int i=; i<lm; ++i)   scanf ("%d", &t[i]);
         printf ("%d\n", KMP (ln, lm));
     }

     return ;
 }

KMP