leetcode/work/Medium/Array/875.koko-eating-bananas.js

/*
 * 875. Koko Eating Bananas
 * Difficulty: Medium
 * https://leetcode.com/problems/koko-eating-bananas/
 * 
 * ──────────────────────────────────────────────────
 * 
 * Koko loves to eat bananas. There are n piles of bananas, the i^th
 * pile has piles[i] bananas. The guards have gone and will come back in
 * h hours.
 * 
 * Koko can decide her bananas-per-hour eating speed of k. Each hour,
 * she chooses some pile of bananas and eats k bananas from that pile. If
 * the pile has less than k bananas, she eats all of them instead and
 * will not eat any more bananas during this hour.
 * 
 * Koko likes to eat slowly but still wants to finish eating all the
 * bananas before the guards return.
 * 
 * Return the minimum integer k such that she can eat all the bananas
 * within h hours.
 * 
 *  
 * 
 * Example 1:
 * 
 * Input: piles = [3,6,7,11], h = 8
 * Output: 4
 * 
 * Example 2:
 * 
 * Input: piles = [30,11,23,4,20], h = 5
 * Output: 30
 * 
 * Example 3:
 * 
 * Input: piles = [30,11,23,4,20], h = 6
 * Output: 23
 * 
 *  
 * 
 * Constraints:
 * 
 * 	• 1 <= piles.length <= 10^4
 * 
 * 	• piles.length <= h <= 10^9
 * 
 * 	• 1 <= piles[i] <= 10^9
*/

/**
 * @param {number[]} piles
 * @param {number} h
 * @return {number}
 */
var minEatingSpeed = function(piles, h) {
  // Function to determine if K works for the H
   function kWorks(k){
    let hours = 0;
    for (let p of piles){
      hours += Math.ceil(p/k)
    }
    return hours <= h;
  }

  // Setup Binary Search
  let l = 1;
  let r = Math.max(...piles);

  // Find the K value which works for H and consumes all bananas
  while (l < r){
    const mid = Math.floor((l + r) / 2);
    if (kWorks(mid)){
      r = mid;
    }else{
      l = mid + 1;
    }
  }
  return l;
};