 # Array - 123. Best Time to Buy and Sell Stock III

123. Best Time to Buy and Sell Stock III

Say you have an array for which the _i_th 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.

java：

``````class Solution {

public int maxProfit(int[] prices) {
if (prices == null || prices.length == 0) return 0;

int[] dp = new int;
int[] min = new int[]{prices, prices, prices};

for (int i = 0; i < prices.length; i++) {
for (int k = 1; k <= 2; k++) {
dp[k] = Math.max(dp[k], prices[i] - min[k]);
min[k] = Math.min(min[k], prices[i] - dp[k-1]);
}
}
return dp;
}
}
``````

Nothing just happens, it's all part of a plan.