LeetCode-in-Go
188. Best Time to Buy and Sell Stock IV
Hard
You are given an integer array prices where prices[i] is the price of a given stock on the ith day, and an integer k.
Find the maximum profit you can achieve. You may complete at most k transactions.
Note: You may not engage in multiple transactions simultaneously (i.e., you must sell the stock before you buy again).
Example 1:
Input: k = 2, prices = [2,4,1]
Output: 2
Explanation: Buy on day 1 (price = 2) and sell on day 2 (price = 4), profit = 4-2 = 2.
Example 2:
Input: k = 2, prices = [3,2,6,5,0,3]
Output: 7
Explanation: Buy on day 2 (price = 2) and sell on day 3 (price = 6), profit = 6-2 = 4. Then buy on day 5 (price = 0) and sell on day 6 (price = 3), profit = 3-0 = 3.
Constraints:
0 <= k <= 1000 <= prices.length <= 10000 <= prices[i] <= 1000
Solution
func maxProfit(k int, prices []int) int {
n := len(prices)
dp := make([]int, k+1)
maxdp := make([]int, k+1)
for i := 0; i <= k; i++ {
maxdp[i] = -1 << 31
}
for i := 1; i <= n; i++ {
maxdp[0] = max(maxdp[0], dp[0]-prices[i-1])
for j := k; j >= 1; j-- {
maxdp[j] = max(maxdp[j], dp[j]-prices[i-1])
dp[j] = max(maxdp[j-1]+prices[i-1], dp[j])
}
}
return dp[k]
}
func max(a, b int) int {
if a > b {
return a
}
return b
}