FZU2236 第十四个目标 dp+树状数组优化

#include <cstdio>
#include <cstring>
#include <queue>
#include <set>
#include <map>
#include <stack>
#include <cstdlib>
#include <algorithm>
#include <vector>
#include <cmath>
using namespace std;
typedef long long LL;
typedef pair<int,int>pii;
const int N=1e5+5;
const int INF=0x3f3f3f3f;
const int mod=1000000007;
int p[N],n,a[N],c[N];
int cnt;
void add(int x,int t){
   for(int i=x;i<=cnt;i+=i&(-i))
     c[i]=(c[i]+t)%mod; 
}
int ask(int x){
    if(x==0)return 0;
    int ans=0;
    for(int i=x;i>0;i-=i&(-i))
      ans=(ans+c[i])%mod;
    return ans; 
}
int main(){
    while(~scanf("%d",&n)){
      for(int i=1;i<=n;++i)
        scanf("%d",&a[i]),p[i]=a[i];
      sort(p+1,p+1+n);
      cnt=unique(p+1,p+1+n)-p-1;
      memset(c,0,sizeof(c));
      int ans=0;
      for(int i=1;i<=n;++i){
         int pos=lower_bound(p+1,p+1+cnt,a[i])-p;
         int tmp=(ask(pos-1)+1)%mod;
         add(pos,tmp);
         ans=(ans+tmp)%mod;
      }
      printf("%d\n",ans); 
    }
    return 0;
}