Leetcode 1870. 准时到达的列车最小时速（DAY 185）---- 二分查找学习期

• • 原题题目
  • 代码实现（首刷自解）

class Solution {
public:
    bool can_arrive(vector& dist,double hour,int speed)
    {
        if(!speed)  return false;
        double arrive_hours = 0;
        for(const auto& num:dist)
        {
            arrive_hours += (double)num/speed;
            if(arrive_hours > hour) return false;
            arrive_hours = ceil(arrive_hours);
        }
        return true;
    }

    int minSpeedOnTime(vector& dist, double hour) {
        int left = 0,right = pow(10,7);
        while(left < right)
        {
            int mid = (left + right)/2;
            if(can_arrive(dist,hour,mid))   right = mid;
            else left = mid+1;
        }
        return can_arrive(dist,hour,left) ? left : -1;
    }
};