JZYZOJ 1360 [usaco2011feb]人品问题 DP 树状数组 离散化

http://172.20.6.3/Problem_Show.asp?id=1360

 

好想好写

 

代码

 #include<iostream>
 #include<cstdio>
 #include<cstring>
 #include<algorithm>
 #include<cmath>
 #include<queue>
 using namespace std;
 const int maxn=;
 const long long modn=;
 long long n,siz;
 long long a[maxn]={},b[maxn]={};
 long long t[maxn]={};
 long long lowbit(long long x){return x&-x;}
 long long sum(long long x){
     long long tsn=;
     while(x){
         tsn+=t[x];tsn%=modn;
         x-=lowbit(x);
     }return tsn;
 }
 void add(long long x,long long v){
     while(x<=siz){
         t[x]+=v;t[x]%=modn;
         x+=lowbit(x);
     }
 }
 int main(){
     scanf("%d",&n);
     for(int i=;i<=n;i++){
         scanf("%I64d",&a[i]);
         a[i]+=a[i-];b[i]=a[i];
     }b[n+]=;
     sort(b+,b++n);
     siz=unique(b+,b++n)-b-;
     for(int i=;i<=n;i++){
         a[i]=lower_bound(b+,b++siz,a[i])-b;
     }long long zer=lower_bound(b+,b++siz,)-b;
     add(zer,);
     long long x;
     for(int i=;i<=n;i++){
         x=sum(a[i]);
         if(i==n){
             printf("%I64d\n",x);
             break;
         }
         add(a[i],x);
     }
     return ;
 }