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\n",ans%Mod);

    }

    return 0;

}