Time Cost

20min38s

Implementation

The solution’s time complexity is n*log(n). Some boundaries should be noticed such as “hour_needed” could be over maximum integer.

Code

• My Solution

  class Solution {
  public:
    int minEatingSpeed(vector<int>& piles, int h) {
        // n*logn
        int base = 1, ceil = 0;
        for (int pile: piles) {
            ceil = max(ceil, pile);
        }
  
        int bisec = (base + ceil) / 2;
        long hour_needed = 0;
        int result = INT_MAX;
        double a = 0.0;
        int b = 0;
        while (base <= ceil) {
            for (int pile: piles) {
                a = static_cast<double>(pile) / static_cast<double>(bisec);
                b = static_cast<int>(std::ceil(a));
                hour_needed += b;
            }
            if (hour_needed <= h) {
                result = min(result, bisec);
                ceil = bisec - 1;
                bisec = (base + ceil) / 2;
            }else{
                base = bisec + 1;
                bisec = (base + ceil) / 2;
            }
            hour_needed = 0;
        }
        return result;
    }
  };