122 Best Time to Buy and Sell Stock II.js

// Say you have an array for which the ith element is the price of a given stock on day i.

// Design an algorithm to find the maximum profit. You may complete as many transactions as you like (i.e., buy one and sell one share of the stock multiple times).

// Note: You may not engage in multiple transactions at the same time (i.e., you must sell the stock before you buy again).

// Example 1:

// Input: [7,1,5,3,6,4]
// Output: 7
// Explanation: Buy on day 2 (price = 1) and sell on day 3 (price = 5), profit = 5-1 = 4.
//              Then buy on day 4 (price = 3) and sell on day 5 (price = 6), profit = 6-3 = 3.
// Example 2:

// Input: [1,2,3,4,5]
// Output: 4
// Explanation: Buy on day 1 (price = 1) and sell on day 5 (price = 5), profit = 5-1 = 4.
//              Note that you cannot buy on day 1, buy on day 2 and sell them later, as you are
//              engaging multiple transactions at the same time. You must sell before buying again.
// Example 3:

// Input: [7,6,4,3,1]
// Output: 0
// Explanation: In this case, no transaction is done, i.e. max profit = 0.

/**
 * @param {number[]} prices
 * @return {number}
 */
var maxProfit = function(prices) {
  if (prices === null || prices.length === 0) {
    return 0;
  }

  var profit = 0;

  for (var i = 1; i < prices.length; i++) {
    var diff = prices[i] - prices[i - 1];
    if (diff > 0) {
      profit += diff;
    }
  }

  return profit;
};