Best Time to Buy - Leetcode Problem

Best Time to Buy

//https://leetcode.com/problems/best-time-to-buy-and-sell-stock/
// in progress, almost there!

/**
 * @param {number[]} prices
 * @return {number}
 */
var maxProfit = function(prices) {
  let currentBest = 0;
  //let pricesCopy = [...prices]
  for(let i = 0; i < prices.length; i++){
    console.log('prices[i]', prices[i])
    console.log(Math.max(...prices))
    if(Math.max(...prices)-prices[i] > currentBest){
      currentBest =  Math.max(...prices)-prices[i];
      console.log('currentBest:', currentBest)
      
    }
    prices.shift();
   
  }
  return currentBest
};

maxProfit([7,1,5,3,6,4])

This seems to work, but it is still too slow and exceeds time limit.

Spoiler

const maxProfit = function(prices) {
let currentBest = 0;
for (let i = 0; i < prices.length; i++) {
  let diff = Math.max(...prices.slice(i + 1)) - prices[i]
  if (diff > currentBest) {
    currentBest = diff
  }
}
return currentBest
};

This works and is very fast! Going through the array backwards made it so much easier.

Spoiler

const maxProfit = function(prices) {
let profit = 0
let highPrice = 0
for (let i = prices.length - 1; i >= 0; i--) {
  if (prices[i] > highPrice) highPrice = prices[i]
  if (highPrice - prices[i] > profit) profit = highPrice - prices[i]
}
return profit
};