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#include <iostream>
#include <vector>
#include <cmath>

class Solution {
public:
    long long repairCars(std::vector<int>& ranks, int cars) {
        int n = ranks.size();
        long long left = 1, right = 0x3fff'ffff;
        for (long long r : ranks) {
            right = std::min(right, r);
        }
        right *= (long long)cars * cars;
        
        for (long long mid = (left + right); right > left;) {
            if (check(ranks, cars, mid)) {
                right = mid;
            }
            else {
                left = mid + 1;
            }
            mid = (left + right) / 2;
        }
        
        return left;
    }
    
private:
    bool check(std::vector<int>& ranks, int cars, long long time) {
        for (int r : ranks) {
            cars -= (int)std::sqrt(time / r);
            if (cars <= 0) {
                return true;
            }
        }
        return false;
    }
};