【BZOJ】【P3670】【Noi2014】【动物园】【题解】【KMP+树状数组】

传送门:http://www.lydsy.com/JudgeOnline/problem.php?id=3670

求出next数组后把next[i]->i连边建成一棵树,num[i]就是i到根的<=i/2的点的个数,放眼望去就只有我一个傻逼用树状数组?其他的都是线性的?算了能过就是好算法

Code:

#include<bits/stdc++.h>
using namespace std;
const int maxn=1e6+5;
int T,n;
int next[maxn],num[maxn];
char s[maxn];
typedef long long LL;
LL p=1000000007;
vector<int>G[maxn];
#define lowbit(x) (x&-x)
int d[maxn];
int get(int x){
	int ans=0;while(x)ans+=d[x],x-=lowbit(x);
	return ans;
}
void updata(int x,int f){
	if(x)
	while(x<=n)d[x]+=f,x+=lowbit(x);
}
void dfs(int u){
	num[u]=get(u/2);
	updata(u,1);
	for(int i=0;i<G[u].size();i++)
		dfs(G[u][i]);
	updata(u,-1);
}
int main(){
	scanf("%d",&T);
	while(T--){
		scanf("%s",s+1);n=strlen(s+1);
		for(int i=0;i<=n;++i)G[i].clear();
		G[0].push_back(1);
		for(int i=2,j=0;i<=n;i++){
			while(j&&s[i]!=s[j+1])j=next[j];
			next[i]=j+=s[i]==s[j+1];
			G[next[i]].push_back(i);
		}dfs(0);
		LL ans=1;
		for(int i=1;i<=n;i++)
			ans=(LL)ans*(num[i]+1)%p;
		cout<<ans<<endl;
	}
	return 0;
}