A1050 String Subtraction

1050 String Subtraction （20 分)

Given two strings S​1​​ and S​2​​, S=S​1​​−S​2​​ is defined to be the remaining string after taking all the characters in S​2​​ from S​1​​. Your task is simply to calculate S​1​​−S​2​​ 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 S​1​​ and S​2​​, respectively. The string lengths of both strings are no more than 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 S​1​​−S​2​​ in one line.

Sample Input:

They are students.
aeiou

Sample Output:

Thy r stdnts.

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

bool hashtable[128] = {0};

int main()
{
	string a, b;
	getline(cin, a);
	getline(cin, b);
	int lena = a.size(), lenb = b.size();
	for(int i =0; i<lenb; i++){
		hashtable[b[i]] = true;
	} 
	for(int i=0; i<lena; i++){
		if(hashtable[a[i]] == false)
			printf("%c", a[i]);
	}
	return 0;
}