PAT（甲级）2017年春季考试

PAT（甲级）2017年春季考试

A.Raffle for Weibo Followers

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

int m,n,s;
vector<string> person;
set<string> se;
vector<string> ans;

int main(){
	cin>>m>>n>>s;
	for(int i=1;i<=m;i++){
		string name;
		cin>>name;
		person.push_back(name);
	}
	int num = person.size();
//	for(int i=0;i<num;i++) cout<<person[i]<<endl; 
	if(s > num) puts("Keep going...");
	else{
		int pos = s-1;
		while(pos < num){
			if(se.find(person[pos]) == se.end()){
				se.insert(person[pos]);
//				cout<<pos<<endl;
				ans.push_back(person[pos]);
				pos = pos + n;
			}else{
				pos++;
			}
		}
		for(int i=0;i<ans.size();i++) cout<<ans[i]<<endl;
	}
	
	return 0;
} 

B.Chain the Ropes优先队列

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

priority_queue<int,vector<int>,greater<int> > que;

int n;

int main(){
	cin>>n;
	for(int i=1;i<=n;i++){
		int d;
		cin>>d;
		que.push(d);
	}
	while(que.size() != 1){
		int fir = que.top();
		que.pop();
		int sec = que.top();
		que.pop();
		int thir = (fir + sec)/2;
		que.push(thir);
	}
	cout<<que.top();
	return 0;
}

C.Eulerian Path

还没做，统计度数来判断是不是欧拉回路，dfs判断是否连通图

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

const int maxn = 520;
int n,m;
vector<int> g[maxn];
int degree[maxn];
int odd = 0,even = 0;
bool vis[maxn];
int cnt = 0;

void dfs(int x){
	vis[x] = true;
	cnt++;
	for(int i=0;i<g[x].size();i++){
		if(vis[g[x][i]] == false) dfs(g[x][i]);
	}
}

int main(){
	cin>>n>>m;
	for(int i=1;i<=m;i++){
		int u,v;
		cin>>u>>v;
		g[u].push_back(v);
		g[v].push_back(u);
		degree[u]++;
		degree[v]++;
	}
	for(int i=1;i<=n;i++){
		if(degree[i]%2 == 0) even++;
		else odd++;
	}
	dfs(1);
	if(n == 0) {
		puts("Non-Eulerian");
		return 0;
	}
	if(n >= 1) cout<<degree[1];
	for(int i=2;i<=n;i++) cout<<" "<<degree[i];
	if(n >= 1) cout<<endl;
	if(even == n && cnt == n) puts("Eulerian");
	else if(odd == 2 && cnt == n) puts("Semi-Eulerian");
	else puts("Non-Eulerian");
	return 0;
} 

D.ZigZagging on a Tree

二叉树，中序后序建树，输出Z字型层次遍历的结果

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

const int maxn = 50;
int n;
int post[maxn];
int in[maxn];
vector<int> ans[maxn];

struct node{
	int v;
	node *l;
	node *r;
};

int maxDepth = 0;

void dfs(node *root,int depth){
	if(depth > maxDepth) maxDepth = depth;
	ans[depth].push_back(root->v);
	if(root->l) dfs(root->l,depth+1);
	if(root->r) dfs(root->r,depth+1);
}

node * build(int root,int il,int ir) {
    if (il > ir) return NULL;
    int pos = il;
    while (pos <= ir && in[pos] != post[root]) 
		pos++;
    node* Root = new node;
    Root->v = post[root];
    Root->r = build(root-1, pos+1,ir );
    Root->l = build(root-(ir-pos)-1 ,il,pos - 1);
    return Root;
}
int main(){
	cin>>n;
	for(int i=1;i<=n;i++) cin>>in[i];
	for(int i=1;i<=n;i++) cin>>post[i];
	node *Root = new node();
	Root = build(n,1,n);
	dfs(Root,1);
	cout<<ans[1][0];
	for(int i=2;i<=maxDepth;i++){
		if(i%2==0){
			for(int j=0;j<ans[i].size();j++){
				cout<<" "<<ans[i][j];
			}
		}else{
			for(int j=ans[i].size()-1;j>=0;j--){
				cout<<" "<<ans[i][j];
			}
		}
	}
	return 0;
}