tokitsukaze and Segmentation
Involving knowledge points:
- Optimization dp / number combination
solution：
- First of all routes to apologize, this item difficulty a bit big QAQ
- Represents the prefix string s1s2 .... si, in this embodiment the number of substrings divided by dp [i]
- If you encounter s [i] is 0, then all the position after position i, the last position is not divided before this position i, subtracting the division number string prefix scheme si-1 to dp [i-1]
std:
#include <bits/stdc++.h>
using namespace std;
#define ll long long
const int maxn = 100005;
const ll mod = 998244353;
char s[maxn];
ll dp[maxn];
int main()
{
int n;
scanf("%d",&n);
scanf("%s",s+1);
ll ans = 1;
int cnt = 0;
dp[0] = 1;
for(int i=1;i<=n;i++){
cnt = (cnt + (s[i]-'0'))%3;
if(cnt)continue ;
dp[i] = ans ;
if(s[i] == '0')
ans = (ans - dp[i-1] + mod)%mod;
ans = (ans + dp[i])%mod;
}
cout<<dp[n]<<endl;
return 0;
}