hdu_2227_Find the nondecreasing subsequences_树状数组,离散化

#include<cstdio>
#include<algorithm>
#define FFC(i,a,b) for(int i=a;i<=b;i++)
#define LL long long
using namespace std;
LL tree[100010];
int maxn,mod=1000000007,l,r,t,len,mid;
int dt[100010],a[100010];
void init(int n){maxn=n;for(int i=0;i<=maxn;i++)tree[i]=0;}
inline void add(int x,int v){for(int i=x;i<=maxn;i+=i&-i)tree[i]=(tree[i]+v)%mod;}
inline LL sum(int x){LL an=0;for(;x>0;x-=x&-x)an=(an+tree[x])%mod;return an;}
inline int lowb(int x){for(l=1,r=len;l<=r;)if(a[mid=(l+r)>>1]>=x)r=(t=mid)-1;else l=mid+1;}
int main(){
int n;
while(~scanf("%d",&n)){
FFC(i,1,n){
scanf("%d",&dt[i]);
a[i]=dt[i];//离散化数组
}
sort(a+1,a+1+n);
len=unique(a+1,a+1+n)-a-1;//离散化
init(len);
LL ans=0;
FFC(i,1,n){
lowb(dt[i]);//二分查找
int tt=sum(t);
add(t,tt+1);
ans=(ans+tt+1)%mod;//注意，一个数它本身也是一个递增子列，所以要加一
}
printf("%lld\n",ans);
}
return 0;
}