On the whole , It was fine in the middle of the game , That is to say, filling in the blanks takes a lot of time , I think the amount of code is very large , Maybe I'm too complicated ? But when we get to the back, it's very explosive , My head is in a mess , I can't concentrate , Maybe it's because I haven't done much recently , Wuwuwu , In the end, I left two questions and didn't do them . Recall the topic , No questions or codes in hand , I can only think about the way of thinking in the game by memory , Code and title , Code to do , The answer may also be wrong , Anyway, it's just for reference .

Updated questions

Save one !

<>A card

<> Title Description

Respectively 2021 individual 0-9, How many words can you spell from the beginning .

<> Brief introduction of thinking

Simple simulation

<> code
#include<bits/stdc++.h> using namespace std; typedef long long LL; typedef
unsigned long long uLL; const int inf=0x3f3f3f3f; const int maxn=1e5+5; const
int N=6e6+5; const LL mod=998244353; const double pi=acos(-1); int n,ans,cnt[15]
,f=1; int main() // 3181 { scanf("%d",&n); //2021 for(int i=0;i<=9;i++) cnt[i]=n
; for(int i=1;i<=inf&&f;i++) { int now=i; while(now) { if(cnt[now%10]) cnt[now%
10]--; else f=0; now/=10; } if(f) ans=i; } printf("%d\n",ans); return 0; }
<> Reference results

3181

<>B straight line

<> Title Description

Two dimensional plane is given 20*21 A point , The number of straight lines formed by questions .

<> Brief introduction of thinking

I'm a couple , Reuse set De duplication record y=kx+b,x=a, These are two straight lines , The end result is s.size();
Code output after the game 48953; In the competition 57561…
I feel as like as two peas . Maybe it's all wrong ? I guess it's too accurate .

<> code
#include<bits/stdc++.h> using namespace std; typedef long long LL; typedef
unsigned long long uLL; const int inf=0x3f3f3f3f; const int maxn=5e6+5; const
int N=1e7+15; const LL mod=998244353; const double eps=1e-7; const double pi=
acos(-1); int n,m; struct node{ double k,b; node(double kk,double bb) { k=kk,b=
bb; } friend bool operator < (node x,node y){ if(fabs(x.k-y.k)<eps) return x.b<y
.b; return x.k<y.k; } }; set<node>s; void solve(int a,int b,int c,int d) { if(a
==c&&b==d) return; if(a==c)//x=a; { if(s.find(node(1.0*inf,1.0*a))!=s.end())
return; s.insert(node(1.0*inf,1.0*a)); } else //y=kx-ka+b; { double kk=1.0*(d-b)
/(c-a); double bb=1.0*kk*a-b; if(s.find(node(kk,bb))!=s.end()) return; s.insert(
node(kk,bb)); } } int main() //20 21 { scanf("%d%d",&n,&m); for(int a=0;a<n;a++)
for(int b=0;b<m;b++) for(int c=0;c<n;c++) for(int d=0;d<m;d++) solve(a,b,c,d);
printf("%d\n",s.size()); return 0; }
<> Reference results

48953 ? It should be wrong

<>C Goods placement

<> Title Description

given n=2021041820210418( It's the date only when the teammate reminds me ), Divide a ∗ b ∗ c a*b*c a∗b∗c Number of Solutions
such as n=4 When I was young
1 1 4;1 4 1;1 1 4;1 2 2;2 1 2;2 2 1 Six methods of classification

<> Brief introduction of thinking

I just got this question , I think it's a big number , But after thinking about the decomposition, there should be no big prime number , I wrote factorization , After the decomposition is
2021041820210418
2 3 3 3 17 131 2857 5882353
After that is to write search , I need to write another one set duplicate removal .

<> code
#include<bits/stdc++.h> using namespace std; typedef long long LL; typedef
unsigned long long uLL; const int inf=0x3f3f3f3f; const int maxn=5e6+5; const
int N=1e7+15; const LL mod=998244353; const double pi=acos(-1); struct node{ int
a,b,c; node(int aa,int bb,int cc) { a=aa,b=bb,c=cc; } friend bool operator < (
node x,node y){ if(x.a==y.a) { if(x.b==y.b) return x.c<y.c; return x.b<y.b; }
return x.a<y.a; } }; set<node>s; LL n,x[5]; int cnt,prime[maxn],res; bool
is_prime[N],f[maxn]; vector<LL>mid; void __prime() { for(int i=1;i<=N-5;i++)
is_prime[i]=1; is_prime[1]=0; for(int i=2;i<=N-5;i++) if(is_prime[i]) { prime[++
cnt]=i; for(int j=i;j<=N-5;j+=i) is_prime[j]=0; } } /* 2021041820210418 2 3 3 3
17 131 2857 5882353 */ void fen(){ LL now=n; for(int i=1;i<=cnt;i++) while(n%
prime[i]==0) n/=prime[i],mid.push_back(1LL*prime[i]); } void dfs(int ff,int now,
LL mul) { if(now==mid.size()) { x[ff]=mul; if(ff==1) { x[2]=n/x[1]/x[0]; if(s.
find(node(x[0],x[1],x[2]))!=s.end()) return; s.insert(node(x[0],x[1],x[2])); res
++; } else dfs(ff+1,0,1); return; } if(f[now]==0) { f[now]=1; dfs(ff,now+1,mul*
mid[now]); f[now]=0; dfs(ff,now+1,mul); } else dfs(ff,now+1,mul); } int main() {
__prime(); scanf("%lld",&n); fen(); for(int i=0;i<mid.size();i++) printf("%d ",
mid[i]); printf("\n"); dfs(0,0,1); printf("%d\n",res); return 0; }
<> Reference results

2430

<>D route

<> Problem description

The difference between the absolute values of two numbers is less than or equal to 21 Edge , The border right is lcm(i,j);
All in all 2021 One point
Ask from 1 reach 2021 The shortest path of

<> Brief introduction of thinking

Simulation mapping , The shortest path is OK .
My teammates told me before the game Bellon-Ford Here we go

And he wrote Freud. Haha
It's amazing

<> code
#include<bits/stdc++.h> using namespace std; typedef long long LL; typedef
unsigned long long uLL; const int inf=0x3f3f3f3f; const int maxn=1e5+5; const
int N=6e6+5; const LL mod=998244353; const double pi=acos(-1); int gcd(int a,int
b){ if(b==0) return a; return gcd(b,a%b); } struct node{ int u,v,w; node(int uu
,int vv,int ww) { u=uu,v=vv,w=ww; } }; int n,dis[maxn]; vector<node>g; int main(
) { scanf("%d",&n); for(int i=1;i<=n;i++) dis[i]=inf; dis[1]=0; for(int i=1;i<=n
;i++) for(int j=i+1;j<=n;j++) { if(j-i>21) continue; g.push_back( node( i , j ,
i*j/gcd(i,j) ) ); } for(int i=1;i<=n-1;i++) { bool f=0; for(int j=0;j<g.size();j
++) { int u=g[j].u,v=g[j].v,w=g[j].w; if(dis[v]>dis[u]+w) f=1,dis[v]=dis[u]+w; }
if(f==0) break; } printf("%d\n",dis[n]); return 0; }
<> Reference results

10266837

<>E Loop count

I didn't do it , I thought I could do it , I want to do a big problem , It blew up in the back , gone for ever .

Now more, now more , I'm writing. I'm writing
When writing big questions, the mentality is a bit broken , I feel that there may be problems in reading .
I don't seem to remember the meaning ...
I can only think of ideas and codes in general , I don't know if I read it right

<>F Weighing with weights

<> Problem description

There is a balance and a pile of weights , Weights can be placed on the left or right . He now knows the weight of each weight . According to the above conditions , How many groups of different weights can be measured .

<> Brief introduction of thinking

dynamic programming ?
The feeling is to write a simple recursion , Just look at the code

The important thing is to survive -sum reach sum bar , So all subscripts are added sum.

<> code
#include<bits/stdc++.h> using namespace std; typedef long long LL; typedef
unsigned long long uLL; const int inf=0x3f3f3f3f; const int maxn=1e3+5; const
int N=3e5+5; const LL mod=998244353; const double pi=acos(-1); vector<int>mid;
int n,res,a[maxn],sum,f[N]; int main() { scanf("%d",&n); for(int i=1;i<=n;i++)
scanf("%d",&a[i]),sum+=a[i]; for(int i=1;i<=n;i++) { mid.clear(); mid.push_back(
sum+a[i]); mid.push_back(sum-a[i]); for(int j=0;j<=2*sum;j++) if(f[j]) { if(j-a[
i]>=0) mid.push_back(j-a[i]); mid.push_back(j+a[i]); } for(int j=0;j<mid.size();
j++) f[mid[j]]=1; } for(int i=sum+1;i<=2*sum;i++) if(f[i]) res++; printf("%d\n",
res); return 0; }
<>G XOR sequence

<> Problem description

Don't hit me if you're wrong , That means I read it wrong, too

A and B Two people are playing games , In the beginning, they each have a number a,b, Give an array x, The person whose turn is in each round can do two operations , Choose an XOR a Or XOR b, Each number can only be used once .A First hand , Multiple input and output .
Under the optimal strategy , Select all the numbers , Who has the biggest number wins , Otherwise it's a draw .

<> Brief introduction of thinking

All numbers are represented in binary , Count by bit . If there's only one at the top , I'm sure it's the first A I won , If there are two at the top , We should go to the next high position . So it's only about the parity of the digits , But that's the way to start A You won't lose at all , I don't know if it's too simple .. Abba, Abba, Abba , It's too delicious .

Wrong
First hand must lose 2 2 2 1
There's nothing left to save

<> code
#include<bits/stdc++.h> // None of the samples were tested using namespace std; typedef long long LL;
typedef unsigned long long uLL; const int inf=0x3f3f3f3f; const int maxn=1e5+5;
const int N=6e6+5; const LL mod=998244353; const double pi=acos(-1); int cnt[30]
,bit[30],n,t,x; int solve() { for(int i=25;i>=0;i--) if(cnt[i]%2) return 0*
printf("1\n"); return 0*printf("0\n"); } int main() { scanf("%d",&t); for(int i=
0;i<=25;i++) bit[i]=1<<i; while(t--) { scanf("%d",&n); memset(cnt,0,sizeof(cnt))
; for(int i=1;i<=n;i++) { scanf("%d",&x); for(int i=25;i>=0;i--) if(x>=bit[i]) x
-=bit[i],cnt[i]++; } solve(); } return 0; }
<>H Left child right brother

<> Problem description

Turn a tree into a binary tree according to left son and right brother . The root height of the tree is 0, Find the highest height of binary tree after transformation .

<> Brief introduction of thinking

structure , Recursive traversal of trees

<> code

Data range , I can't remember the examples and the details of the title , The code is for reference only
#include<bits/stdc++.h> using namespace std; typedef long long LL; const int
inf=0x3f3f3f3f; const int maxn=2e5+5; int n; vector<int>g[maxn]; int dfs(int u)
{ int mx=0,sz=g[u].size(); for(int i=0;i<sz;i++) mx=max(mx,dfs(g[u][i])+sz-1);
return mx+1; } int main() { scanf("%d",&n); for(int i=2,u;i<=n;i++) { scanf("%d"
,&u); g[u].push_back(i); } printf("%d\n",dfs(1)-1); return 0; }
<>I Bracket sequence

The most angry question , I always feel like I can do it , For more than an hour , I still didn't write it , At last, it is simplified to the problem of many line segments and points .
Examples ((()
The last thing that comes out is from [1,2],[1,3] The number of schemes to take two points on two line segments , namely (1,1),(1,2),(1,3),(2,2),(2,3) Five .
Another example (((()

It's from [1,2],[1,3],[1,4] Pick up point , namely (1,1,1),(1,1,2),(1,1,3),(1,1,4),(1,2,2),(1,2,3),(1,2,4),(1,3,3),(1,3,4),(2,2,2),(2,2,3),(2,2,4),(2,3,3),(2,3,4) Fourteen kinds .
But I just don't know how to deduce the formula , In the end, I didn't push out my watch , great , Finally, I wrote a pop search . There's less than half an hour left to finish this , also J and E I didn't touch it .

I don't want to write this question …

<>J Split fruit

<> Problem description

Divide candy
n Grow candy ,m personal , Each candy can be divided up to two times , At least once , Everyone's got to get it , And can only be divided into continuous candy .

<> Brief introduction of thinking

There's no time , There are about ten minutes left after reading the question , Wrote the most violent violence

Explosive search
initialization cnt Arrays are all arrays 2

Enumerate the start and end points when searching , Let's look at the starting point and the ending point , appear cnt[i]=0 This set of starting and ending points is illegal , If it's legal, keep searching , All the way back m personal , From 1 reach n Judge cnt[i]==2 It's not legal , Search for all the information res=min(res,mx-mn)

The time complexity is beyond imagination
probably n=10 It's hard to get out , But there's no time …

<> code

I don't want to write such violent code again
Wait for time to think about it .

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