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 at most two transactions.
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: [3,3,5,0,0,3,1,4] Output: 6 Explanation: Buy on day 4 (price = 0) and sell on day 6 (price = 3), profit = 3-0 = 3. Then buy on day 7 (price = 1) and sell on day 8 (price = 4), profit = 4-1 = 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.
class Solution { public int maxProfit(int[] prices) { int dp_i10 = 0, dp_i11 = Integer.MIN_VALUE; int dp_i20 = 0, dp_i21 = Integer.MIN_VALUE; for(int price:prices){ dp_i20 = Math.max(dp_i20,dp_i21+price); dp_i21 = Math.max(dp_i21,dp_i10-price); dp_i10 = Math.max(dp_i10,dp_i11+price); dp_i11 = Math.max(dp_i11,-price); } return dp_i20; } }
Runtime: 1 ms, faster than 99.83% of Java online submissions for Best Time to Buy and Sell Stock III.
Memory Usage: 37.3 MB, less than 100.00% of Java online submissions for Best Time to Buy and Sell Stock III.