Submission #60048271

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Source Code Expand

#include<bits/stdc++.h>
#define fo(i,l,r) for(int i=l;i<=r;++i)
#define fd(i,r,l) for(int i=r;i>=l;--i)
#define ll long long
#define I inline int
#define V inline void
#define B inline bool
#define L inline ll
#define pi pair<int,int>
#define mk make_pair
#define fi first
#define se second
#define pb push_back
#define vi vector<int>
#define vii vector<pi>
using namespace std;
const int N=1e6+10,mod=998244353;
char St;
I read() {
	int x=0,y=1;char c=getchar();
	while(c<48||c>57) {if(c==45)y=-y;c=getchar();}
	while(c>=48&&c<=57) x=(x<<1)+(x<<3)+(c^48),c=getchar();
	return x*y;
}
int n,a[N],cnt[N];
L ksm(ll x,int y) {ll t(1);for(;y;y>>=1,x=x*x%mod)if(y&1)t=t*x%mod;return t;}
char Ed;
int main() {
	cerr<<"memory:"<<(&St-&Ed)/1024.0<<endl;
	n=read();
	fo(i,1,n) a[i]=read();
	int ans(0),r(0);
	for(int l=1;l<=n;l+=2) {
		r=max(r,l-1);
		while(r+2<=n&&a[r+1]==a[r+2]&&cnt[a[r+1]]==0) cnt[a[r+1]]+=2,r+=2;
		ans=max(ans,r-l+1);
		if(l<=r) cnt[a[l]]--,cnt[a[l+1]]--;
	}
	memset(cnt,0,sizeof(cnt));
	r=0;
	for(int l=2;l<=n;l+=2) {
		r=max(r,l-1);
		while(r+2<=n&&a[r+1]==a[r+2]&&cnt[a[r+1]]==0) cnt[a[r+1]]+=2,r+=2;
		ans=max(ans,r-l+1);
		if(l<=r) cnt[a[l]]--,cnt[a[l+1]]--;
	}
	printf("%d\n",ans);
	cerr<<"time:"<<clock()<<endl;
	return 0;
}

Submission Info

Judge Result