1050. String Subtraction (20)

Given two strings S₁ and S₂, S = S₁ - S₂ is defined to be the remaining string after taking all the characters in S₂from 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 <cstdio>#include <vector>#include <string>#include <algorithm>#include <iostream>#include <map>using namespace std;int main(){    string s1,s2,output;    getline(cin, s1);    getline(cin, s2);    map<char, bool> c_map;    for(int i=0; i<256; i++)c_map.insert(make_pair( i , 1));    for(string::iterator it=s2.begin() ; it!=s2.end() ; ++it)c_map[*it]=0;    for(string::iterator it=s1.begin() ; it!=s1.end() ; ++it)if(c_map[*it])output+=*it;    cout<<output;    return 0;}