Submission #3428176

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Source Code Expand

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cmath>
#define maxn 100010
#define mod 1000000007
#define inf 1000000000000000007
using namespace std;
typedef long long ll;
ll read()
{
    ll x=0,f=1;
    char ch=getchar();
    while(ch-'0'<0||ch-'0'>9){if(ch=='-') f=-1;ch=getchar();}
    while(ch-'0'>=0&&ch-'0'<=9){x=x*10+ch-'0';ch=getchar();}
    return x*f;
}
int n;
ll A,B;
ll a[maxn];
ll f[maxn];
int las1[maxn],las2[maxn];
ll t[maxn*4];
void push_up(int k)
{
    t[k]=(t[k*2]+t[k*2+1])%mod;
}
void modi(int k,int l,int r,int x,ll y)
{
    if(l==r)
    {
        t[k]=y;
        return;
    }
    int mid=(l+r)/2;
    if(mid>=x)  modi(k*2,l,mid,x,y);
    else        modi(k*2+1,mid+1,r,x,y);
    push_up(k);
}
ll query(int k,int l,int r,int x,int y)
{
    if(l>=x&&r<=y)  return t[k];
    int mid=(l+r)/2;
    ll res=0;
    if(mid>=x)   res+=query(k*2,l,mid,x,y);
    res%=mod;
    if(mid<y)    res+=query(k*2+1,mid+1,r,x,y);
    res%=mod;
    return res; 
}
int main()
{
    n=read();A=read();B=read();
    for(int i=1;i<=n;i++)  a[i]=read();
    las1[1]=las2[1]=1;
    for(int i=2;i<=n;i++)
    {
        if(a[i]-a[i-1]>=A)  las1[i]=las1[i-1];
        else las1[i]=i;
        if(a[i]-a[i-1]>=B)  las2[i]=las2[i-1];
        else las2[i]=i;
    }
    f[0]=1;
    f[1]=1;
    a[0]=-inf;
    modi(1,0,n,0,1);
    modi(1,0,n,1,1);
    for(int i=2;i<=n;i++)
    {
        int r=upper_bound(a,a+i+1,a[i]-A)-a;
        r--;
        int l=las2[i-1];
        l--;
        if(l>r)  continue;
        f[i]=query(1,0,n,l,r);
        modi(1,0,n,i,f[i]);
    }
    printf("%lld\n",f[n]);
    return 0;
}

Submission Info

Judge Result