PAT_1050: String Subtraction

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.

備註：簡單題，直接用哈希的思想查找即可。

#include<stdio.h>

int main()
{
	char s1[10005],s2[10005];
	int map[1000]={0};

	gets(s1);
	gets(s2);

	for(int i=0;s2[i]!='\0';i++)
		map[s2[i]]=1;

	for(int i=0;s1[i]!='\0';i++)
	{
		if(map[s1[i]]==0)
			printf("%c",s1[i]);
	}

	return 0;
}