$AC$ $Code$：

#include <bits/stdc++.h>
#define ll long long
#define re register int
#define Rep(x, a, b) for (int x = a; x <= b; x++)
#define Dep(x, a, b) for (int x = a; x >= b; x--)
#define MAXN 100005
using namespace std;
struct T
{
    int d, t;
}a[MAXN];
ll p[MAXN], ans;
int n;
inline bool cmp(T x, T y) { return (double)x.d / x.t * 1.0 > (double)y.d / y.t * 1.0; }
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    cin >> n;
    Rep(i, 0, n - 1)
        cin >> a[i].t >> a[i].d;
    sort(a, a + n, cmp);
    p[0] = a[0].d;
    Rep(i, 1, n - 1)
        p[i] = p[i - 1] + a[i].d;
    Rep(i, 0, n - 1)
        ans += (p[n - 1] - p[i]) * a[i].t * 2;
    cout << ans << endl;
    return 0;
}

#include<bits/stdc++.h>
using namespace std;
int n;
struct node
{
    int t,d;
}a[100001];
bool cmp(node x,node y)
{
    return x.t*y.d<y.t*x.d;
}
int main()
{
    cin>>n;
    for(int i=1;i<=n;i+=1)
    {
        cin>>a[i].t>>a[i].d;
    }
    sort(a+1,a+n+1,cmp);
    long long ans=0,T=0;
    for(int i=1;i<=n;i+=1)
    {
        ans+=T*a[i].d;
        T+=2*a[i].t;
    }
    cout<<ans;
}

AC代码，请放心食用。

#include<bits/stdc++.h>
int n,m,k,s,t;
struct node
{
    int t,d;
}a[100001];
bool cmp(node x,node y)
{
    return x.t*y.d<y.t*x.d;
}
int main()
{
    std::cin>>n;
    for(int i=1;i<=n;i+=1)std::cin>>a[i].t>>a[i].d;
    std::sort(a+1,a+n+1,cmp);
    long long ans=0,T=0;
    for(int i=1;i<=n;i+=1)
    {
        ans+=T*a[i].d;
        T+=2*a[i].t;
    }
    std::cout<<ans;
}