rt,今天学校模拟赛

题面：

#include <cstdio>
#include <algorithm>
using namespace std;
typedef long long ll;

const int N=100010;
const ll Mod=365*24*60*60;
struct Node{
	int a, b;
}q[N];

bool cmp(Node p, Node q){
	return (ll)p.a * q.b < (ll)p.b * q.a;
	//p.a/p.b  < q.a/q.b 
}//以a/b的值升序排序，避免实数除，以乘法代替 
void in(int &x){
	char c=getchar();
	while (c<'0' || c>'9') c=getchar();
	for (x=0; c>='0' && c<='9'; c=getchar())
		x=x*10+c-'0';
}
int main(){
    freopen("exam.in","r",stdin);
    freopen("exam.out","w",stdout);
	int t, n; scanf("%d", &t);
	while (t--){ 
		scanf("%d", &n);
		for (int i=0; i<n; i++)
			in(q[i].a), in(q[i].b);	//scanf("%d %d", &q[i].a, &q[i].b);
		sort(q, q+n, cmp);
		ll sum=0;
		for (int i=0; i<n; i++)		
			sum=(sum+sum*q[i].b+q[i].a)%Mod;
		printf("%lld\n", sum);
	}
	return 0;
}
标程

//#pragma GCC optimize(2)
#include <bits/stdc++.h>
#define ll long long
#define ull unsigned long long
#define ewen using
#define ak namespace
#define ioi std
#define ewen_ak_ioi return 0;
ewen ak ioi;

ll in(){
	char c = getchar();
	ll x = 0, f = 1;
	for (; c < '0' || c > '9'; c = getchar())
		if (c == '-') f = -1;
	for (; c >= '0' && c <= '9'; c = getchar())
		x = (x << 1) + (x << 3) + (c ^ 48);
	return x * f;
}
void put(int x){
	if (x < 0) x = -x, putchar('-');
	if (x > 9) put(x / 10);
	putchar(x % 10 + '0');
}
const ll M=365*24*60*60;
struct Node{
    int a,b;
}a[114514];
bool cmp(Node a,Node b)
{
    return a.a*b.b<b.a*a.b;
}
int main()
{
	freopen("exam.in","r",stdin);
	freopen("exam.out","w",stdout);
	int t;scanf("%d",&t);
	while(t--)
	{
        int n=in();
        for(int i=0;i<n;i++)a[i].a=in(),a[i].b=in();
        sort(a,a+n,cmp);
        ll ans=0;
        for(int i=0;i<n;i++)
            ans=(ans+ans*a[i].b+a[i].a)%M;
        printf("%lld\n",ans);
        for(int i=0;i<n;)a[i].a=a[i++].b=0;
	}
	ewen_ak_ioi
}
//Never gonna give you up
//Never gonna let you down
//Never gonna run around and desert you
//Never gonna make you cry
//Never gonna say good-bye
//Never gonna tell a lie and hurt you
我的（请忽视奇怪的define和注释）

然后我就对3个点，很不理解，求助。

另外说一下，我是@BigPinkCat 小号嗷