【历年CSP-S复赛第一题】暴力解法与正解合集（2019-2022）

1. P5657 [CSP-S2019] 格雷码
2. P7076 [CSP-S2020] 动物园
3. P7913 [CSP-S 2021] 廊桥分配
4. P8817 [CSP-S 2022] 假期计划

P5657 [CSP-S2019] 格雷码

暴力50分

#include<bits/stdc++.h>
#define IOS ios::sync_with_stdio(false),cin.tie(0),cout.tie(0) 
#define int long long
#define PII pair<int,int> 
#define pb push_back
using namespace std;
const int N = 1e6+5;
int n,k;
signed main()
{
	IOS;
	cin>>n>>k;
	vector<string> v;
	v.pb("0");
	v.pb("1");
	for(int j=1;j<=n-1;j++) 
	{
		vector<string> vt;
		for(int i=0;i<(int)v.size();i++)
		{
			vt.pb("0"+v[i]);
		}
		for(int i=(int)v.size()-1;i>=0;i--)
		{
			vt.pb("1"+v[i]);
		}
		v = vt;
	}
	cout<<v[k];
}

正解

#include<bits/stdc++.h>
#define IOS ios::sync_with_stdio(false),cin.tie(0),cout.tie(0) 
#define int long long
#define PII pair<int,int> 
#define pb push_back
using namespace std;
const int N = 1e6+5;
unsigned long long n,k;
signed main()
{
	IOS;
	cin>>n>>k;
	__int128 sum = (__int128)pow(2,n);
	int pre = -1;
	while(1)
	{
		if(pre==-1)
		{
			if(k<=sum/2-1)
			{
				cout<<0;
				pre = -1;
			}
			else
			{
				cout<<1;
				pre = 1;
				k -= sum/2;
			}	
		}
		else
		{
			if(k<=sum/2-1)//k下标从1开始 
			{
				cout<<1;
				pre = -1;
			}
			else
			{
				cout<<0;
				pre = 1;
				k -= sum/2;
			}
		}
		sum /= 2;
		if(sum==1) break;
	}
}

P7076 [CSP-S2020] 动物园

暴力

#include<bits/stdc++.h>
#define IOS ios::sync_with_stdio(false),cin.tie(0),cout.tie(0) 
#define int long long
#define PII pair<int,int> 
#define pb push_back
using namespace std;
const int N = 1e6+5;
int n,m,c,k;
int limit[N],va[N];
signed main()
{
	IOS;
	cin>>n>>m>>c>>k;
	for(int i=1;i<=n;i++) cin>>va[i];
	while(m--)
	{
		int a,b;
		cin>>a>>b;
		limit[a] = b;//动物编号第a为1就必须有b号饲料 
	}
	set<int> s;
	for(int i=1;i<=n;i++)//由已有动物来倒推我有哪些饲料
	{
		for(int j=0;j<=k-1;j++)
		{
			if((va[i]>>j)&1)//动物编号的二进制第j位为1 
			{
				s.insert(limit[j]);//动物编号的二进制第j位为1,即需要limit[j]号饲料
			}
		}
	}
	int sum = 0;
	for(int i=0;i<=pow(2,k)-1;i++)
	{
		int suc = 1;
		for(int j=0;j<=k-1;j++)
		{
			if((i>>j)&1)
			{
				if(limit[j]==0) continue;
				if(s.count(limit[j])) continue;
				suc = 0;
			}
		}
		if(suc==1) sum++;
	}
	cout<<sum-n;
}

正解

#include<bits/stdc++.h>
#define IOS ios::sync_with_stdio(false),cin.tie(0),cout.tie(0) 
#define int long long
#define PII pair<int,int> 
#define pb push_back
using namespace std;
const int N = 1e6+5;
int n,m,c,k;
int limit[N],va[N];
bool vis[N];
signed main()
{
	IOS;
	cin>>n>>m>>c>>k;
	for(int i=1;i<=n;i++) cin>>va[i];
	while(m--)
	{
		int a,b;
		cin>>a>>b;
		limit[a] = b;//动物编号第a为1就必须有b号饲料 
	}
	for(int j=0;j<=k-1;j++)
	{
		if(limit[j]==0) vis[j] = 1;
		for(int i=1;i<=n;i++)
		{
			if((va[i]>>j)&1) vis[j] = 1;//由已有动物来倒推我哪些位置有哪些饲料
		}
	}
	int sum = 0;
	for(int i=0;i<=k-1;i++)
	{
		if(vis[i]==1) sum++;
	}
	if(sum==64)
	{
		if(n==0) cout<<"18446744073709551616";
		else cout<<(1ull<<(sum-1))-n+(1ull<<(sum-1));
	}
	else cout<<(1ull<<sum)-n;
}

P7913 [CSP-S 2021] 廊桥分配

暴力

#include<bits/stdc++.h>
#define IOS ios::sync_with_stdio(false),cin.tie(0),cout.tie(0) 
#define int long long
#define PII pair<int,int> 
#define pb push_back
using namespace std;
const int N = 1e6+5;
int n,m1,m2;
struct node{
	int in;
	int out;
}va[N],vb[N];
bool cmp(node a,node b)
{
	return a.in<b.in;
}
int solve(int sum1,int sum2)
{
	int ans = 0;
	priority_queue <int,vector<int>,greater<int> > q1,q2;
	for(int i=1;i<=m1;i++) 
	{ 
		while(q1.size()&&q1.top()<=va[i].in) q1.pop();
		if(q1.size()<sum1)
		{
			ans++;
			q1.push(va[i].out);
		}
	}
	for(int i=1;i<=m2;i++) 
	{ 
		while(q2.size()&&q2.top()<=vb[i].in) q2.pop();
		if(q2.size()<sum2)
		{
			ans++;
			q2.push(vb[i].out);
		}
	}
	return ans;
}
signed main()
{
	IOS;
	cin>>n>>m1>>m2;
	int maxn = 0;
	for(int i=1;i<=m1;i++)
	{
		cin>>va[i].in>>va[i].out;
	}
	for(int i=1;i<=m2;i++)
	{
		cin>>vb[i].in>>vb[i].out;
	}
	sort(va+1,va+1+m1,cmp);
	sort(vb+1,vb+1+m2,cmp);
	for(int i=0;i<=n;i++)
	{
		maxn = max(maxn,solve(i,n-i));
	}
	cout<<maxn;
}

正解

#include<bits/stdc++.h>
#define PII pair<int,int>
#define fi first
#define se second
#define int long long

using namespace std;

const int N = 1e5+10;

int n,m1,m2;
PII va[N],vb[N];
int cnt1[N],cnt2[N];

priority_queue<PII,vector<PII>,greater<PII>> q1,q2;

int solve1()
{
	for(int i=1;i<=n;i++) q1.push({0,i});
	for(int i=1;i<=m1;i++)
	{
		int min_id = 1e9;
		vector<PII > v;
		while(q1.size()&&q1.top().fi<=va[i].fi)
		{
			v.push_back(q1.top());
			if(min_id>q1.top().se) min_id = q1.top().se;
			q1.pop();
		}
		for(auto t:v)
		{
			if(t.se==min_id) q1.push({va[i].se,t.se});
			else q1.push({0,t.se});
		}
		if(min_id!=1e9) cnt1[min_id]++;
	}
	for(int i=1;i<=n;i++) cnt1[i] = cnt1[i]+cnt1[i-1];
}

int solve2()
{
	for(int i=1;i<=n;i++) q2.push({0,i});
	for(int i=1;i<=m2;i++)
	{
		int min_id = 1e9;
		vector<PII > v;
		while(q2.size()&&q2.top().fi<=va[i].fi)
		{
			v.push_back(q2.top());
			if(min_id>q2.top().se) min_id = q2.top().se;
			q2.pop();
		}
		for(auto t:v)
		{
			if(t.se==min_id) q2.push({va[i].se,t.se});
			else q2.push({0,t.se});
		}
		if(min_id!=1e9) cnt2[min_id]++;
	}
	for(int i=1;i<=n;i++) cnt2[i] = cnt2[i]+cnt2[i-1];
}

signed main()
{
//	freopen("w.in","r",stdin);
//  freopen("ho.out","w",stdout);
	cin>>n>>m1>>m2;
	for(int i=1;i<=m1;i++) cin>>va[i].fi>>va[i].se;
	for(int i=1;i<=m2;i++) cin>>vb[i].fi>>vb[i].se;
	sort(va+1,va+1+m1);
	sort(vb+1,vb+1+m2);
	solve1();solve2();
	int anw = 0;
	for(int i=0;i<=n;i++) anw = max(anw,cnt1[i]+cnt2[n-i]);
	cout<<anw;
	return 0;
}