PAT (Class A) 2019 Spring exam

7-1 Sexy Primes a point not determined prime number points through 17/20

#include<bits/stdc++.h>
using namespace std;

const int maxn = 1e8;
typedef long long ll;
int n;

bool isprime(ll x){
    if(x == 0 || x==1 || x==2) return false;
    for(ll i=2;i<=sqrt(x);i++){
        if(x%i==0) return false;
    }
    return true;
}

int main(){
    scanf("%lld",&n);
    if(isprime(n)){
        if(n>=6 && isprime(n-6)){
            puts("Yes");
            printf("%lld",n-6);
        }else if(isprime(n+6)){
            puts("Yes");
            printf("%lld",n+6);
        }else{
            puts("No");
            for(ll i=n+1;i<=maxn;i++){
                if(i-6>=0){
                    if((i-6)>=0 && isprime(i) && isprime(i-6)){
                        printf("%lld",i);
                        break;
                    }
                }else{
                    if(isprime(i) && isprime(i+6)){
                        printf("%lld",i);
                        break;
                    }
                }
            }
        }
    }else{
        puts("No");
        for(ll i=n+1;i<=maxn;i++){
            if(i-6>=0){
                if((i-6)>=0 && isprime(i) && isprime(i-6)){
                    printf("%lld",i);
                    break;
                }
            }else{
                if(isprime(i) && isprime(i+6)){
                    printf("%lld",i);
                    break;
                }
            }
        }
    }
    return 0;
} 

7-2 Anniversary collection, sorting to find 25 points

#include<bits/stdc++.h>
using namespace std;

set<string> se1;
set<string> se2;
int n,m;

int main(){
    cin>>n;
    for(int i=1;i<=n;i++){
        string id;
        cin>>id;
        se1.insert(id);
    }
    int ans = 0;
    string guestold = "99999999";
    string assold = "99999999";
    string guest;
    string ass;
    cin>>m;
    for(int i=1;i<=m;i++){
        string id;
        cin>>id;
        se2.insert(id);
        string temp;
        for(int j=6;j<=13;j++) temp.push_back(id[j]);
        if(se1.find(id) != se1.end()){
            ans++;
            if(assold > temp) {
                assold = temp;
                ass = id;
            }
        }
        if(guestold > temp) {
            guestold = temp;
            guest = id;
        }
    }
    cout<<ans<<endl;
    if(ans != 0){
        if(n !=0){
            cout<<ass<<endl;
        }
    }else{
        if(m!=0){
            cout<<guest<<endl;
        }
    }
    return 0;
}

7-3 Telefraud Detection graph theory 15/25 points

#include<bits/stdc++.h>
using namespace std;

/*
邻接矩阵
点:出度 和他的边相关的入度
*/

const int maxn = 1010;
int k,n,m;
int g[maxn][maxn];
vector<int> sss;
int vis[maxn];
vector<int> temp;
set<int> se;


void print(){
    if(temp.size()==0) return;
    cout<<temp[0];
    for(int i=1;i<temp.size();i++){
        cout<<" "<<temp[i];
    }
    cout<<endl;
}

int main(){
    cin>>k>>n>>m;
    for(int i=1;i<=m;i++){
        int u,v,w;
        cin>>u>>v>>w;
        g[u][v] = w;
    }
    for(int i=1;i<=n;i++){
        int call = 0;
        int back = 0;
        for(int j=1;j<=n;j++){
            if(g[i][j]!=0 && g[i][j] <= 5){
                call++;
                if(g[j][i] != 0) back++;
            }
        }
        if(call > k && back*5 <= call){
            sss.push_back(i);
            se.insert(i);
        }
    }
    if(sss.size() == 0){
        cout<<"None"<<endl;
        return 0;
    }
    sort(sss.begin(),sss.end());
    for(int i=0;i<sss.size();i++){
        int x = sss[i];
        temp.clear();
        if(!vis[x]){
            vis[x] = 1;
            temp.push_back(x);
            for(int j=i+1;j<sss.size();j++){
                //判断第sss[i]能否可以用 
                bool can = true;
                for(int k=0;k<temp.size();k++){
                    if(g[sss[j]][temp[k]] == 0){
                        can = false;
                        break;
                    }
                }
                if(can == true){
                    vis[sss[j]] = 1;
                    temp.push_back(sss[j]);
                }
            }
            print();
        }
    }
    return 0;
}

7-4 Structure of binary tree after a Binary Tree Sequence Number contribution, dfs deep search 30

#include<bits/stdc++.h>
using namespace std;

int n,m;
const int maxn = 1100;
int in[maxn];
int post[maxn];

struct node{
    int v;
    node* l;
    node* r;
};
int level[maxn];
int l[maxn];
int r[maxn];
int sib[maxn];
int par[maxn];
bool full = true;

void dfs(node *root,int depth){
    if(root == NULL) return;
    int x = root->v;
    level[x] = depth;
    if(root->l != NULL){
        par[root->l->v] = x;
        l[x] = root->l->v;
        dfs(root->l,depth+1);
    }
    if(root->r != NULL){
        par[root->r->v] = x;
        r[x] = root->r->v;
        dfs(root->r,depth+1);
    }
    if(root->l != NULL && root->r != NULL){
        sib[root->l->v] = root->r->v;
        sib[root->r->v] = root->l->v;
    }
    if((root->l == NULL && root->r !=NULL) || (root->r == NULL && root->l !=NULL) ){
        full = false;
    }
}

node* build(int il,int ir,int pl,int pr){
    if(il > ir) return NULL;
    int rootv = post[pr];
    int pos = il;
    while(pos <= ir && in[pos] != rootv) pos++;
    node *root = new node;
    root->v = rootv;
    root->l = build(il,pos-1,pl,pr-(ir-pos)-1);
//  pr-(ir-pos)+1
//  root->r = build(pos+1,ir,pl+(pos-il)+1,pr);
    root->r = build(pos+1,ir,pr-(ir-pos)+1,pr-1);
    return root;
}

int main(){
    cin>>n;
    for(int i=1;i<=n;i++) cin>>post[i];
    for(int j=1;j<=n;j++) cin>>in[j];
    node* Root = build(1,n,1,n);
    dfs(Root,1);
    cin>>m;
    getchar();
    while(m--){
        string stat;
        getline(cin, stat);
        if(stat.find("root") != string::npos){
            int root = 0;
            for(int i=0;i<stat.length();i++){
                if(stat[i] > '9' ||  stat[i] < '0') break;
                root = root*10 + (stat[i] - '0');
            }
            if(root == Root->v){
                puts("Yes");
            }else{
                puts("No");
            }
        }else if(stat.find("siblings") != string::npos){
            int parent = 0;
            int pos = 0;
            for(int i=0;i<stat.length();i++){
                if(stat[i] > '9' ||  stat[i] < '0') break;
                parent = parent*10 + (stat[i] - '0');
                pos = i;
            }
            int child = 0;
            for(int i = pos+1;i<stat.length();i++){
                if(stat[i] > '9' ||  stat[i] < '0') continue;
                child = child*10 + (stat[i] - '0');
            }
            if(sib[parent] == child && sib[child] == parent){
                puts("Yes");
            }else{
                puts("No");
            }
        }else if(stat.find("parent") != string::npos){
            int parent = 0;
            int pos = 0;
            for(int i=0;i<stat.length();i++){
                if(stat[i] > '9' ||  stat[i] < '0') break;
                parent = parent*10 + (stat[i] - '0');
                pos = i;
            }
            int child = 0;
            for(int i = pos+1;i<stat.length();i++){
                if(stat[i] > '9' ||  stat[i] < '0') continue;
                child = child*10 + (stat[i] - '0');
            }
            if(par[child] == parent){
                puts("Yes");
            }else{
                puts("No");
            }
        }else if(stat.find("left") != string::npos){
            int parent = 0;
            int pos = 0;
            for(int i=0;i<stat.length();i++){
                if(stat[i] > '9' ||  stat[i] < '0') break;
                parent = parent*10 + (stat[i] - '0');
                pos = i;
            }
            int child = 0;
            for(int i = pos+1;i<stat.length();i++){
                if(stat[i] > '9' ||  stat[i] < '0') continue;
                child = child*10 + (stat[i] - '0');
            }
            if(l[child] == parent){
                puts("Yes");
            }else{
                puts("No");
            }
        }else if(stat.find("right") != string::npos){
            int parent = 0;
            int pos = 0;
            for(int i=0;i<stat.length();i++){
                if(stat[i] > '9' ||  stat[i] < '0') break;
                parent = parent*10 + (stat[i] - '0');
                pos = i;
            }
            int child = 0;
            for(int i = pos+1;i<stat.length();i++){
                if(stat[i] > '9' ||  stat[i] < '0') continue;
                child = child*10 + (stat[i] - '0');
            }
            if(r[child] == parent){
                puts("Yes");
            }else{
                puts("No");
            }
        }else if(stat.find("same") != string::npos){
            int parent = 0;
            int pos = 0;
            for(int i=0;i<stat.length();i++){
                if(stat[i] > '9' ||  stat[i] < '0') break;
                parent = parent*10 + (stat[i] - '0');
                pos = i;
            }
            int child = 0;
            for(int i = pos+1;i<stat.length();i++){
                if(stat[i] > '9' ||  stat[i] < '0') continue;
                child = child*10 + (stat[i] - '0');
            }
            if(level[parent] == level[child]){
                puts("Yes");
            }else{
                puts("No");
            }
        }else if(stat.find("full") != string::npos){
            if(full) puts("Yes");
            else puts("No");
        }
        
    }
    return 0;
}