HDU6170-Two strings

Two strings

Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/65536 K (Java/Others)
Total Submission(s): 274 Accepted Submission(s): 90

Problem Description
Giving two strings and you should judge if they are matched.
The first string contains lowercase letters and uppercase letters.
The second string contains lowercase letters, uppercase letters, and special symbols: “.” and “*”.
. can match any letter, and * means the front character can appear any times. For example, “a.b” can match “acb” or “abb”, “a*” can match “a”, “aa” and even empty string. ( “” will not appear in the front of the string, and there will not be two consecutive “”.

Input
The first line contains an integer T implying the number of test cases. (T≤15)
For each test case, there are two lines implying the two strings (The length of the two strings is less than 2500).

Output
For each test case, print “yes” if the two strings are matched, otherwise print “no”.

Sample Input
3
aa
a*
abb
a.*
abb
aab

Sample Output
yes
yes
no

Source
2017 Multi-University Training Contest - Team 9

题目大意：问给出的正则表达式能否匹配文本。
解题思路：利用C++regex，注意.∗不能匹配ab

#include<iostream>#include<cstdio>#include<algorithm>#include<cstring>#include<string>#include<regex>using namespace std;const int MAXN=2600;string s,p;int main(){    int T;    cin>>T;    while(T--)    {        cin>>s>>p;        string s1=".*";        string s2="(a*|b*|c*|d*|e*|f*|g*|h*|i*|j*|k*|l*|m*|n*|o*|p*|q*|r*|s*|t*|u*|v*|w*|x*|y*|z*"                  "|A*|B*|C*|D*|E*|F*|G*|H*|I*|J*|K*|L*|M*|N*|O*|P*|Q*|R*|S*|T*|U*|V*|W*|X*|Y*|Z*)";        //string s2="(.)\\1*";        int len=s2.length();        auto pos=p.find(s1);        while(pos!=string::npos)        {            p.replace(pos,2,s2);            pos=p.find(s1,pos+len);        }        regex pat(p);        if(regex_match(s,pat)) cout<<"yes"<<endl;        else cout<<"no"<<endl;    }    return 0;}