【离散数学】单射、满射和双射的定义、区别

【Books】推荐书单（算法、JavaWeb、Python爬虫、机器学习、程序人生、人文社科）

edjxj:

你怎么看的这么多书，我不太信

1076. Wifi密码 (15)-PAT乙级真题

柠石榴:

没有柳神这么强的思路，还是用的n

[code=cpp]

#include

using namespace std;

int main(){

int n;

cin >> n;

cin.ignore();

while (n --){

string s;

getline(cin, s);

for (int i = 0; i < s.size(); i ++)

if (s[i] == 'T') cout << s[i - 2] - 'A' + 1;

}

return 0;

}

[/code]

PAT 1067. 试密码(20)-乙级

柠石榴:

[code=cpp]

#include

using namespace std;

int main(){

string s,t;

int n;

cin >> s >> n;

cin.ignore();

for (int i = 1; ; i ++)

{

getline(cin, t);

if (t == "#") break;

else if (t == s){

cout << "Welcome in" << endl;

break;

}

else{

cout << "Wrong password: " << t << endl;

if (i == n){

cout << "Account locked" << endl;

break;

}

}

}

return 0;

}

[/code]

1115 裁判机 – PAT乙级真题

夜一森:

difficult

1039. 到底买不买（20）-PAT乙级真题

柠石榴:

用的哈希表，不过思路跟柳神一样

[code=cpp]

#include

using namespace std;

int main()

{

string s1, s2;

cin >> s1 >> s2;

map mp;

for (int i = 0; i < s1.size(); i ++) mp[s1[i]] ++;

int sum = 0;

for (int i = 0; i < s2.size(); i ++)

if (mp[s2[i]] != 0) mp[s2[i]] --;

else sum ++;

if (sum == 0) cout << "Yes" << " " << s1.size() - s2.size() << endl;

else cout << "No" << " " << sum << endl;

return 0;

}

[/code]