考研编程练习---StringMatching(后缀表达式)

题目描述：

Finding all occurrences of a pattern in a text is a problem that arises frequently in text-editing programs.
    Typically,the text is a document being edited,and the pattern searched for is a particular word supplied by the user.  
    We assume that the text is an array T[1..n] of length n and that the
pattern is an array P[1..m] of length m<=n.We further assume that
the elements of P and  T are all alphabets(∑={a,b...,z}).The character
arrays P and T are often called strings of characters.  
    We say that pattern P occurs with shift s in the text T if
0<=s<=n and T[s+1..s+m] = P[1..m](that is if T[s+j]=P[j],for
1<=j<=m).  
    If P occurs with shift s in T,then we call s a valid shift;otherwise,we calls a invalid shift. 
    Your task is to calculate the number of vald shifts for the given text T and p attern P.

输入：

For each case, there are two strings T
and P on a line,separated by a single space.You may assume both the
length of T and P will not exceed 10^6.

输出：

You should output a number on a separate line,which indicates the number of valid shifts for the given text T and pattern P.

样例输入：

abababab abab

样例输出：

3

经典代码：

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

string t,p;
string s;

int main(int argc,char* argv[]){
    while(cin>>t>>p){
        int c = 0;
        for(int i=0;i<t.length()-p.length()+1;i++){
            s = t.substr(i,p.length());
            if(p==s){
                c++;
            }
        }
        cout<<c<<endl;
    }
    return 0;
}