1 PAT 甲级 1116 Come on! Let’s C

#include <bits/stdc++.h>
using namespace std;
map<int,string> mp; 
bool is_prime[10010];
void Init(){
    fill(is_prime,is_prime+10010,true);
    is_prime[0]=is_prime[1]=false;
    for(int i=2;i<10010;++i){
        if(is_prime[i]){
            for(int j=i*2;j<10010;j+=i){
                is_prime[j]=false;
            }
        }
    }
}

int main() {
    Init();
    int n;cin>>n;
    for(int i=1;i<=n;++i){
        int tmp;cin>>tmp;
        if(i==1) mp[tmp]="Mystery Award";
        else if(is_prime[i]) mp[tmp]="Minion";
        else mp[tmp]="Chocolate";
    }
    int k;cin>>k;
    while(k--){
        int tmp;cin>>tmp;
        if(mp.count(tmp)==0) printf("%04d: Are you kidding?\n",tmp);
        else{
            printf("%04d: %s\n",tmp,mp[tmp].c_str());
            mp[tmp]="Checked";
        }
    }
}

2 PAT 甲级 1117 Eddington Number

#include <bits/stdc++.h>
using namespace std;
int mile[100010];
int main() {
    int n;cin>>n;
    for(int i=0;i<n;++i) cin>>mile[i];
    sort(mile,mile+n,[](int a,int b){return a>b;});
    int ans=0;
    while(ans<n&&mile[ans]>ans+1) ++ans;
    cout<<ans;
}

3 PAT 甲级 1118 Birds in Forest

#include <bits/stdc++.h>
using namespace std;
set<int> birds;
int father[10010];
int Find(int x){
    if(father[x]!=x) father[x]=Find(father[x]);
    return father[x];
}
int Union(int a,int b){
    father[Find(a)]=Find(b);
}
int main() {
    for(int i=0;i<10010;++i) father[i]=i;
    int n;cin>>n;
    for(int i=0;i<n;++i){
        int k;cin>>k;int b0,bt;
        for(int i=0;i<k;++i){
            cin>>bt;
            if(i==0) b0=bt;
            else Union(b0,bt);
            birds.insert(bt);
        }
    }
    set<int> trees;
    for(auto i:birds){
        trees.insert(Find(i));
    }
    cout<<trees.size()<<" "<<birds.size()<<"\n";
    int q;cin>>q;
    while(q--){
        int x,y;
        cin>>x>>y;
        if(Find(x)==Find(y)) cout<<"Yes\n";
        else cout<<"No\n";
    }
}

4 PAT 甲级 1119 Pre-and Post-order Traversals

#include <bits/stdc++.h>
using namespace std;
int lchild[50],rchild[50];
int pre[50],post[50];
map<int,int> key,val;
bool multi=false;
void Build(int l1,int r1,int l2,int r2){
    if(l1==r1){
        lchild[l1]=rchild[l1]=-1;
        return;
    }
    int root=pre[l1],lc=pre[l1+1],rc=post[r2-1];
    int idx=l2;
    while(idx<r2&&post[idx]!=lc) ++idx;
    if(idx==r2-1){
        multi=true;
        lchild[root]=lc;
        rchild[root]=-1;
        Build(l1+1,l1+1+idx-l2,l2,idx);
    }else{
        lchild[root]=lc;
        rchild[root]=rc;
        Build(l1+1,l1+1+idx-l2,l2,idx);
        Build(l1+1+idx-l2+1,r1,idx+1,r2-1);
    }
}
vector<int> ans;
void InOrder(int root){
    if(lchild[root]!=-1) InOrder(lchild[root]);
    ans.push_back(val[root]);
    if(rchild[root]!=-1) InOrder(rchild[root]);
}
int main() {
    int n;cin>>n;
    for(int i=0;i<n;++i){
        int tmp;cin>>tmp;
        key[tmp]=i,val[i]=tmp;
        pre[i]=i;
    }
    for(int i=0;i<n;++i){
        int tmp;cin>>tmp;
        post[i]=key[tmp];
    }
    Build(0,n-1,0,n-1);
    if(multi) cout<<"No\n";
    else cout<<"Yes\n";
    InOrder(pre[0]);
    for(int i=0;i<n;++i){
        if(i!=0) cout<<" ";
        cout<<ans[i];
    }
    cout<<"\n";
}