1050 String Subtraction

Posted 2020-11-29 ruruozhenhao

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 1. 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.

题意：

　　给出两个字符串，提出第一个字符串中，两个字符串都出现的字符。

思路：

　　模拟。

Code：

 1 #include <bits/stdc++.h>
 2 
 3 using namespace std;
 4 
 5 int main() {
 6     string s1, s2;
 7     getline(cin, s1);
 8     getline(cin, s2);
 9     unordered_set<char> visited;
10     for (int i = 0; i < s2.length(); ++i) visited.insert(s2[i]);
11     string ans = "";
12     for (int i = 0; i < s1.length(); ++i)
13         if (visited.find(s1[i]) == visited.end()) ans += s1[i];
14     cout << ans << endl;
15     return 0;
16 }