关于这个题

#include <iostream>
#include <algorithm>
#define LL long long
using namespace std;

double a[200010], b[200010];
LL c[200010];
int id[200010];

int main()
{
    int t;
    cin >> t;
    while (t--)
    {
        int n;
        cin >> n;
        for (int i = 1; i <= n; i++)
        {
            id[i] = i;
            cin >> a[i] >> b[i];
//------------------------------------
            a[i] += i * 0.000029;
            b[i] += i * 0.000037;
//------------------------------------
        }
        sort(id + 1, id + n + 1, [](int x, int y)
             { return min(a[x], b[y]) < min(a[y], b[x]); });
        LL sum = 0;
        for (int x = 1; x <= n; x++)
        {
            sum += a[id[x]];
            if (x == 1)
            {
                c[1] = a[id[1]] + b[id[1]];
            }
            else
            {
                c[x] = max(c[x - 1], sum) + b[id[x]];
            }
        }
        // for (int i = 1; i <= n; i++)
        // {
        //     cout << id[i] << ' ';
        // }
        // cout << '\n';
        // for (int i = 1; i <= n; i++)
        // {
        //     cout << c[i] << ' ';
        // }
        // cout << '\n';
        cout << c[n] << '\n';
    }
    return 0;
}