Submission #436399

#	Time	Username	Problem	Language	Result	Execution time	Memory
436399		keta_tsimakuridze	Exam (eJOI20_exam)	C++14	100 / 100	213 ms	15784 KiB

exam

#include<bits/stdc++.h>
#define f first
#define s second
using namespace std;
const int N=5000+5,M=1e5+5,mod=1e9+7;
int t,b[M],a[M],dp[N],ans,n,tree[4*M],r[M],l[M];
map<int,vector<int> > c;
bool ok(int x,int y) {
	if(x<=y && r[x] > y) return 1;
	if(x>y && l[x]<y) return 1;
	return 0;
}
void update(int u,int ind,int l,int r,int val) {
	if(l>ind || r<ind) return;
	if(l==r) {
		tree[u] = val;
		return;
	}
	int mid=(l+r)/2;
	update(2*u,ind,l,mid,val);
	update(2*u+1,ind,mid+1,r,val);
	tree[u] = max(tree[2*u],tree[2*u+1]);
}
int getans(int u,int start,int end,int l,int r){
	if(l>end || r<start) return 0;
	if(start<=l && r<=end) return tree[u];
	int mid = (l+r)/2;
	return max(getans(2*u,start,end,l,mid),getans(2*u+1,start,end,mid+1,r));
}
 main(){
 	ios_base::sync_with_stdio(false),cin.tie(0),cout.tie(0);
	cin>>n;
	int F = 0;
	for(int i=1;i<=n;i++) {
		cin >> a[i];
	}
	int f = 0;
	for(int i=1;i<=n;i++){
		cin >> b[i];
		if(i-1 && b[i]!=b[i-1]) f = 1;
	} 
	for(int i=1;i<=n;i++) {
		int x = i - 1;
		while(x && a[x] <= a[i]) {
			x = l[x];
		}
		l[i] = x;
	}
	for(int i=n;i>=1;i--){
		int x = i + 1;
		while(x<=n &&  a[x]<=a[i]) {
			x = r[x];
		}
		r[i] = x;
	}
	int ans = 0;
	//f = 1;
	if(!f) {
	
		for(int i=1;i<=n;i++){
			int j = i - 1,F = 0;
			while(j<n && a[j+1] <= b[1]) {
				j ++;
				if(b[1]==a[j]) F = 1;
			}
			if(F) ans += j - i + 1;
			i = max(i,j);
		}
		cout<<ans;
		return 0;
	}	
	for(int i=1;i<=n;i++){
		if(c[a[i]].size()) F = 1;
 		c[a[i]].push_back(i);
		
	}
	if(!F) { 
		for(int i=1;i<=n;i++) {
			if(c[b[i]].size() && ok(c[b[i]][0],i)) {
				int x = getans(1,1,c[b[i]][0],1,n);
				update(1,c[b[i]][0],1,n,x + 1);
			}
		}
		cout<<tree[1];
		
		return 0;
	}

	for(int i=1;i<=n;i++) {
		for(int j=c[b[i]].size() - 1;j>=0;j--) {
			int ind = c[b[i]][j];
			dp[ind] = dp[ind] + ok(ind,i);
		}
		for(int j=1;j<=n;j++) {
			dp[j] = max(dp[j],dp[j-1]);
			ans = max(dp[j],ans);
			
		} //cout<<endl;
	}
	cout<<ans;
}

Compilation message (stderr)

exam.cpp:30:2: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   30 |  main(){
      |  ^~~~

• Subtask 1: 14 / 14
• Subtask 2: 12 / 12
• Subtask 3: 13 / 13
• Subtask 4: 23 / 23
• Subtask 5: 16 / 16
• Subtask 6: 22 / 22