PAT 解题报告 1050. String Subtraction (20)

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 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.

题意

给定两个字符串，S1 和 S2,要求将 S2 中的字符从 S1 串中剔除。

分析

用 Hash 的方式标记需要剔除的字符。

#include <iostream>
#include <cstdio>
#include <string>

using namespace std;

int main()
{
    int hs[256] ={0};
    char cs[10001];
    gets(cs);
    string st = cs;
    //getline(cin, st);
    while (1) {
        char c = getchar();
        if (c == '
') break;
        hs[c] = 1;
    }

    for (int i=0; i<st.size(); i++) {
        if (hs[st[i]] == 0)
            printf("%c", st[i]);
    }

    return 0;
}