hdu 3450 树状数组

思路：二分查找位置，之后是裸的树状数组。

#include<set>
#include<map>
#include<cmath>
#include<queue>
#include<cstdio>
#include<vector>
#include<string>
#include<cstdlib>
#include<cstring>
#include<iostream>
#include<algorithm>
#define pb push_back
#define mp make_pair
#define Maxn 100010
#define Maxm 200010
#define LL int
#define Abs(x) ((x)>0?(x):(-x))
#define lson(x) (x<<1)
#define rson(x) (x<<1|1)
#define inf 100000
#define lowbit(x) (x&(-x))
#define clr(x,y) memset(x,y,sizeof(x))
#define Mod 9901
using namespace std;
int val[Maxn],sorted[Maxn],n,cnt;
LL C[Maxn];
void update(int pos,LL val)
{
    int i;
    while(pos<=n){
        C[pos]+=val;
        C[pos]%=Mod;
        pos+=lowbit(pos);
    }
}
LL Sum(int pos)
{
    LL sum=0;
    while(pos){
        sum+=C[pos];
        pos-=lowbit(pos);
        sum%=Mod;
    }
    return sum;
}
int main()
{
    int d,i,j;
    while(scanf("%d%d",&n,&d)!=EOF){
        clr(C,0);
        for(i=1;i<=n;i++){
            scanf("%d",val+i);
            sorted[i]=val[i];
        }
        sort(sorted+1,sorted+n+1);
        cnt=1;
        for(i=2;i<=n;i++)
            if(sorted[i]!=sorted[cnt])
            sorted[++cnt]=sorted[i];
        int l,r,pos;
        LL ans=0,temp;
        pos=lower_bound(sorted+1,sorted+cnt+1,val[1])-sorted;
        update(pos,1);
        for(i=2;i<=n;i++){
            temp=0;
            l=lower_bound(sorted+1,sorted+cnt+1,val[i]-d)-sorted;
            r=lower_bound(sorted+1,sorted+cnt+1,val[i]+d)-sorted;
            pos=lower_bound(sorted+1,sorted+cnt+1,val[i])-sorted;
            if(sorted[l]>=val[i]-d) l--;
            if(sorted[r]>val[i]+d||r>cnt) r--;
            LL rr=Sum(r);
            LL ll=Sum(l);
            temp+=(rr-ll+Mod);
            update(pos,temp+1);
            ans+=temp;
            ans%=Mod;
        }
        printf("%d
",ans%Mod);
    }
    return 0;
}