bzoj2096[Poi2010]Pilots*

 1 #include <cstdio>
 2 #include <cstring>
 3 #include <algorithm>
 4 #define inc(i,j,k) for(int i=j;i<=k;i++)
 5 #define maxn 3000010
 6 using namespace std;
 7 
 8 inline int read(){
 9     char ch=getchar(); int f=1,x=0;
10     while(ch<‘0‘||ch>‘9‘){if(ch==‘-‘)f=-1; ch=getchar();}
11     while(ch>=‘0‘&&ch<=‘9‘)x=x*10+ch-‘0‘,ch=getchar();
12     return f*x;
13 }
14 struct nd{int v,pos;};
15 int n,a[maxn],k,l,r,ans,ql1,qr1,ql2,qr2; nd q1[maxn],q2[maxn];
16 int main(){
17     k=read(); n=read(); inc(i,1,n)a[i]=read();
18     l=1; r=1; ans=1; ql1=qr1=ql2=qr2=1; q1[1]=q2[1]=(nd){a[1],1};
19     while(r<n){
20         r++;
21         while(ql1<=qr1&&ql2<=qr2&&a[r]-q1[ql1].v>k){l++; if(l>q1[ql1].pos)ql1++; if(l>q2[ql2].pos)ql2++;}
22         while(ql1<=qr1&&ql2<=qr2&&q2[ql2].v-a[r]>k){l++; if(l>q1[ql1].pos)ql1++; if(l>q2[ql2].pos)ql2++;}
23         ans=max(ans,r-l+1);
24         while(ql1<=qr1&&a[r]<=q1[qr1].v)qr1--; q1[++qr1]=(nd){a[r],r};
25         while(ql2<=qr2&&a[r]>=q2[qr2].v)qr2--; q2[++qr2]=(nd){a[r],r};
26     }
27     printf("%d",ans); return 0;
28 }