772A - Voltage Keepsake - CodeForces Solution

//Jay A Patel
#include<bits/stdc++.h>
using namespace std;


typedef long long int ll;

#define Fast ios::sync_with_stdio(0); cin.tie(0);
#define fr(a, b, c) for(int(a) = (b); (a) < (c); ++(a))
#define fre(a, b) for (auto&(a) : (b))
#define pi 3.1415926536
#define tc ll t; cin>>t; while(t--)

const ll template_array_size = 1e6 + 4265;
int a[template_array_size]; 
int cnt[template_array_size];
int b[template_array_size];
int n,m,h,k,mn=15000009,target,x,y,p;

const int MX = 2e5+10;
priority_queue<pair<int,int>> q;

#define diff 1e-6

int main(){
    
    cin>>n>>p;

    fr(i,1,n+1) cin>>a[i]>>b[i];
    double l=0,r=1e12;
    
    while(r-l>diff) {
        
        double mid = (l+r)/2,need=0;
        
        fr(i,1,n+1) {
            if(b[i]>=a[i]*mid) continue;
            need+=a[i]*mid-b[i];
        }
        if(need<=p*mid)l=mid;
        else r=mid;
    }

    if(l>9e11)cout<<"-1"<<'\n';
    else cout<<l<<'\n';

}