Analysis of Pat computer problems in Zhejiang University 1050. String subtraction (20)

1050. String subtraction (20) Time limit 10 MS
The memory limit is 32000 kb.
Code length limit: 16000 B
Criterion

Given two strings S1 and S2, S = S1-S2 is defined to be the remaining string after taking all the characters in S2 from S1. your task is simply to calculate
S1-S2 for any given strings. However, it might not be that simple to do it
Fast.

Input specification:

Each input file contains one test case. Each case consists of two lines which gives S1 and S2, respectively. The string lengths of both strings are no more than 104. it is guaranteed that all
The characters are visible ASCII codes and white space, and a new line character signals the end of a string.

Output specification:

For each test case, print S1-S2 in one line.

Sample input:

They are students.aeiou

Sample output:

Thy r stdnts.

#include <iostream>#include <string>#include <vector>#include <algorithm>using namespace std;string str1;string str2;string::iterator it1,it2;bool compare(char ch){for (it2=str2.begin();it2!=str2.end();it2++)if (ch == *it2)return true;return false;}int main(){ getline(cin,str1); getline(cin,str2); sort(str2.begin(),str2.end()); str2.erase(unique(str2.begin(),str2.end()),str2.end());str1.resize(remove_if(str1.begin(),str1.end(),compare) - str1.begin()); cout<<str1<<endl;  //system("pause");return 0;}