PTA B (1059 C language race (20 minutes) (map.find (), vector in Find))

A, vector of find

Note find not a member of vector, and is present in the algorithm, should be added to the header file #include <algorithm>

 1 #include <vector>
 2 #include <algorithm>
 3 #include <iostream>
 4 using namespace std;
 5 int main( )
 6 {
 7     vector<int> L;
 8     L.push_back( 1 );
 9     L.push_back( 2 );
10     L.push_back( 3 );
11     L.push_back( 4 );
12     L.push_back( 5 );
13     vector<int>::iterator result = find( L.begin( ), L.end( ), 3 ); //查找3
14     if ( result == L.end( ) ) 
15         cout << "No" << endl;
16     else 
17         cout << "Yes" << endl;
18 }

Two, map.find () and map.count () method

Use find, it is returned to find the position of the element, no map.end return ();

Use count, the return is to find the number of elements. If so, return 1; otherwise, it returns 0. Note that, map does not exist in the same element, so the return value can only be 1 or 0.

 1 // map::find
 2 #include <iostream>
 3 #include <map>
 4 
 5 int main ()
 6 {
 7   std::map<char,int> mymap;
 8   std::map<char,int>::iterator it;
 9 
10   mymap['a']=50;
11   mymap['b']=100;
12   mymap['c']=150;
13   mymap['d']=200;
14 
15   it = mymap.find('b');
16   if (it != mymap.end())
17     mymap.erase (it);
18 
19   // print content:
20   std::cout << "elements in mymap:" << '\n';
21   std::cout << "a => " << mymap.find('a')->second << '\n';
22   std::cout << "c => " << mymap.find('c')->second << '\n';
23   std::cout << "d => " << mymap.find('d')->second << '\n';
24 
25   return 0;
26 }

 1 #include<string>
 2 #include<cstring>
 3 #include<iostream>
 4 #include<map>
 5 #include<algorithm>
 6 using namespace std;
 7 int main(){
 8     map<string,int> mp;
 9     mp.insert(make_pair("a",1));
10     mp.insert(make_pair("b",2));
11     map<string,int>::iterator it;
12     cout<<mp.count("a")<<endl;
13     mp.insert(make_pair("a",2));
14     it=mp.find("a");
15     if(it==mp.end()) cout<<"No!"<<endl;
16     else cout<<it->second<<endl;
17     cout<<mp.count("a")<<endl;
18     return 0;
19 }

Three, 1059 C language competition (20 points)

https://pintia.cn/problem-sets/994805260223102976/problems/994805269828059136

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <string>
 5 #include <cmath>
 6 #include <algorithm>
 7 #include <vector>
 8 #include <map>
 9 bool is_prime(int a)
10 {
11     int i;
12     for(i=2;i<=(int)(sqrt(a));i++)
13     {
14         if(a%i==0) return false;
15     }
16     if(i>(int)(sqrt(a))) return true; 
17 }
18 using namespace std;
19 int main()
20 {
21     int n,k;
22     string str;
23     bool flag[10002]={false};
24     cin>>n;
25     map<string,int> mp;
26     for(int i=1;i<=n;i++) 
27     {
28         cin>>str;
29         mp[str]=i;
30         flag[i]=false;
31     }
32     cin>>k;
33     for(int i=0;i<k;i++)
34     {
35         cin>>str;
36         if(mp.find(str)!=mp.end())
37         {
38             if(flag[mp[str]]==true) cout<<str<<": Checked\n";
39             else{
40                 flag[mp[str]]=true;
41                 if(mp[str]==1) cout<<str<<": Mystery Award\n";
42                 else if(is_prime(mp[str])) cout<<str<<": Minion\n";
43                 else cout<<str<<": Chocolate\n"; 
44             }
45         }
46         else cout<<str<<": Are you kidding?\n";
47     }
48     return 0;
49 }