请问各位大佬，为什么下面两段代码可以达到相同的效果？

#include<bits/stdc++.h>
typedef long long ll;
using namespace std;

int main(){
	ios::sync_with_stdio(false);
	cin.tie(nullptr); cout.tie(nullptr);
	ll n,t,t2,ans;
	int nn; cin>>nn;
	for(int i=0;i<nn;i++){
		cin>>n;
		if(n<1)n=1-n;
		
		if(n<4)goto nextcode;
		
		t=(n-3)/5;
		ans=t*(t+1)/2*5;
		t2=n-t*5-3;
		t++;
		ans+=t2*t;
		
		cout<<ans;
	nextcode:
		switch (n%5) {
		case 1:
			cout<<20;
			break;
		case 2:
			cout<<40;
			break;
		case 3:
			cout<<80;
			break;
		case 4:
			cout<<40;
			break;
		default:
			cout<<20;
			break;
		}
		cout<<'\n';
	}

	return 0;
}

#include<bits/stdc++.h>
using namespace std;
int main(){
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	long long n,a;
	cin>>n;
	for(int i=0;i<n;i++){
		cin>>a;
		cout<<10*a*a-10*a+20<<'\n';
	}


	return 0;
}