2 5 1 2 3 4 6 10 1 1 1 1 1 1 2 3 4 5
4 6
暴力
#include<cstdio> #include<cstring> #include<cstdlib> #include<algorithm> #include<functional> #include<iostream> #include<cmath> #include<cctype> #include<ctime> using namespace std; #define For(i,n) for(int i=1;i<=n;i++) #define Fork(i,k,n) for(int i=k;i<=n;i++) #define Rep(i,n) for(int i=0;i<n;i++) #define ForD(i,n) for(int i=n;i;i--) #define RepD(i,n) for(int i=n;i>=0;i--) #define Forp(x) for(int p=pre[x];p;p=next[p]) #define Forpiter(x) for(int &p=iter[x];p;p=next[p]) #define Lson (x<<1) #define Rson ((x<<1)+1) #define MEM(a) memset(a,0,sizeof(a)); #define MEMI(a) memset(a,127,sizeof(a)); #define MEMi(a) memset(a,128,sizeof(a)); #define INF (2139062143) #define F (100000007) #define MAXN (1000000+10) typedef long long ll; ll mul(ll a,ll b){return (a*b)%F;} ll add(ll a,ll b){return (a+b)%F;} ll sub(ll a,ll b){return (a-b+llabs(a-b)/F*F+F)%F;} void upd(ll &a,ll b){a=(a%F+b%F)%F;} int a[MAXN],b[MAXN]; double c[MAXN]; int main() { // freopen("B.in","r",stdin); int n,T; cin>>T; while (T--) { cin>>n; For(i,n) scanf("%d",&a[i]); int ans=min(2,n); For(i,n-1) b[i]=a[i]-a[i+1]; int p=2; Fork(i,2,n-1) if (b[i]==b[i-1]) ans=max(ans,++p);else p=2; For(i,n-1) c[i]=(double)a[i]/(double)a[i+1]; p=2; Fork(i,2,n-1) if (fabs(c[i]-c[i-1])<1e-8) ans=max(ans,++p); else p=2; cout<<ans<<endl; } return 0; }