hihocoder 1015题

代码

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

 int KMP(const string &pattern,const string &str)
 {
     const int len1 = pattern.length();
     const int len2 = str.length();
     vector<int> next(len1);
     next[]=;
     int i,j,k;
     for (i=;i<len1;i++)
     {
         k=next[i-];
         while (pattern[i] != pattern[k]&&k!=)
         {
             k=next[k-];
         }
         if(pattern[i] == pattern[k])
             next[i]=k+;
         else
             next[i]=;
     }
     i=j=;
     int mycount=;
     while (j < len2)
     {
         if (pattern[i]!=str[j])
         {
             if (i==)
             {
                 i=;
                 j++;
             }
             else
                 i=next[i-];
         }
         else
         {
             i++;
             j++;
             if(pattern[i] == '\0')
             {
                 mycount++;
                 i=next[len1-];//为什么取pattern最后一个字符的next，自己想
                 //i赋值位next[len1-1]是为了防止j回溯
             }
         }
     }

     return mycount;
 }

 int main()
 {
     int n;
     string pattern,str;
     while (cin >> n)
     {
         while (n--)
         {
             cin >> pattern >> str;
             cout << KMP(pattern,str)<<endl;
         }
     }
     return ;
 }