CODE FESTIVAL 2017 qual B B – Problem Set

确实水题，但当时没想到map，用sort后逐个比较解决的，感觉麻烦些，虽然效率高很多。map确实好写点。

用map：

 #include<iostream>
 #include<cstdio>
 #include<cstdlib>
 #include<map>
 using namespace std;
 map<int,int>mp; int main()
 {
     int n,m,x;
     cin>>n;
     for(int i=;i<n;i++){
         cin>>x;
         mp[x]++;
     }
     cin>>m;
     for(int i=;i<m;i++){
         cin>>x;
         if(mp[x]==){
             cout<<"NO"<<endl;
             exit();
         }else mp[x]--;
     }
     cout<<"YES"<<endl;
     return ;
 }

直接sort

 #include<cstdio>
 #include<algorithm>
 using namespace std;
 const int maxn = ;
 int d[maxn], t[maxn]; int main()
 {
     int N, M;
     scanf("%d", &N);
     for (int i = ; i <= N; i++) scanf("%d", &d[i]);
     scanf("%d", &M);
     for (int i = ; i <= M; i++) scanf("%d", &t[i]);
     sort(d+,  + N+d);
     sort(t+,  + M+t);
     int p1 = , p2 = ;
     bool flag = false;
     while (p1<=M&&p2<=N)
     {
         if (p1 != M) {
             if (d[p2] == t[p1]) {
                 p2++, p1++;
             }
             else {
                 p2++;
             }
         }
         else
         {
             if (d[p2] == t[p1]) {
                 flag = true;
                 break;
             }
             else
             {
                 p2++;
             }
         }
     }
     if (flag) printf("YES\n");
     else printf("NO\n");
     return ;
 }