算法之美--3.2.2 MP算法

这块硬骨头，放在这里半年的时间了，一直没有动，今天周末看看，书上把过程写的比较详细，自己基本也看懂了，但是对代码本身的编写还是比较生疏，要经常复习，估计才能看透，后面有看了kmp;这两者之间的关系也是头大。。。

 /*!
  * \file MP_算法.cpp
  *
  * \author ranjiewen
  * \date 2017/02/12 15:06
  *
  *
  */

 void preMp(const char *pattern, int m, int mpNext[]) //m为pattern的长度
 {
     int i, j;
     i = ;
     j = mpNext[] = -;
     while (i<m)
     {
         while (j>-&&pattern[i]!=pattern[j]) //
         {
             j = mpNext[j];
         }
         mpNext[++i] = ++j;  //mpNext(j)=f(j-1)+1
     }
 }

 #include <iostream>
 #include <string>
 using namespace std;

 void MP(string pattern, string target)
 {
     int m = pattern.length();
     int n = target.length();
     if (m>n)
     {
         cerr << "Unsuccessful match!" << endl;
         return;
     }
     const char* x = pattern.c_str();
     const char* y = target.c_str();
     int i = , j = , mpNext[];  //m+1大小

     preMp(x, m, mpNext);  //mpNext 进行一下轮比较过程中模式P的起始比较位置

     bool flag = false;
     while (i<n)   //i 遍历target字符串
     {
         while (j>-&&x[j]!=y[i])  //j 匹配模式字符串
         {
             j = mpNext[j];
         }
         j++;
         i++;

         if (j>=m)
         {
             cout << "Matching index found at:" << i - j << endl;
             j = mpNext[j];  //匹配后面的子串
             flag = true;
         }
     }
     if (!flag)
     {
         cout << "Unsuccessful match=-====!";
     }
 }

 int main(int argc, char** argv)
 {
     string p1 = "abcabcad";
     string p2 = "adcadcad";
     string p3 = "ababcaabc";
     string t = "ctcabcabcadtcaabcabcaaatabcabcad";

     cout << "MP_p1 : " << endl;
     MP(p1, t);
     cout << endl;

     cout << "MP_p2 : " << endl;
     MP(p2, t);
     cout << endl;

     cout << "MP_p3 : " << endl;
     MP(p3, t);
     cout << endl;

     string t1 = "ctcaatcacaatcat";
     string p4 = "caatcat";
     MP(p4, t1);
     cout << endl;
     return ;
 }