F - Predilection(dp)

Posted 2022-01-01 Harris-H

F - Predilection(dp)

比较显然的线性dp，但是我一开始不会。

开一个去重map即可。

// Problem: F - Predilection
// Contest: AtCoder - AtCoder Beginner Contest 230
// URL: https://atcoder.jp/contests/abc230/tasks/abc230_f
// Memory Limit: 1024 MB
// Time Limit: 2000 ms
// Date: 2021-12-06 17:21:30
// --------by Herio--------

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long ull; 
const int N=2e5+5,M=2e4+5,inf=0x3f3f3f3f,mod=998244353;
const int hashmod[4] = 402653189,805306457,1610612741,998244353;
#define mst(a,b) memset(a,b,sizeof a)
#define PII pair<int,int>
#define PLL pair<ll,ll>
#define x first
#define y second
#define pb emplace_back
#define SZ(a) (int)a.size()
#define rep(i,a,b) for(int i=a;i<=b;++i)
#define per(i,a,b) for(int i=a;i>=b;--i)
#define ios ios::sync_with_stdio(false),cin.tie(nullptr) 
void Print(int *a,int n)
	for(int i=1;i<n;i++)
		printf("%d ",a[i]);
	printf("%d\\n",a[n]); 

template <typename T>		//x=max(x,y)  x=min(x,y)
void cmx(T &x,T y)
	if(x<y) x=y;

template <typename T>
void cmn(T &x,T y)
	if(x>y) x=y;

int n;
unordered_map<ll,ll>mp;
ll f[N];
int main()
	ll s;
	scanf("%d%lld",&n,&s);
	f[1] = 1;
	for(int i=2;i<=n;i++)
		int x;scanf("%d",&x);
		f[i] = ((f[i-1]<<1) - mp[s] + mod)%mod;
		mp[s] = f[i-1];
		s+=x;
	
	printf("%lld\\n",f[n]);
	return 0;