2019蓝桥真题C++大学B组 C题 数列求值

#include<iostream>
#include<cstdio>
typedef long long ll;
const ll max=1e9;
ll a[max];
using namespace std;
int  main(){
	a[1]=a[2]=a[3]=1;
	for(ll i=4;i<=20190324;i++)
	{
		a[i]=a[i-1]+a[i-2]+a[i-3];
		a[i]%=10000;
	}	
	ll t=a[20190324]%10000;
	cout<<t;
}