Here, We see Best Time to Buy and Sell Stock IV LeetCode Solution. This Leetcode problem is done in many programming languages like C++, Java, JavaScript, Python, etc. with different approaches.

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Best Time to Buy and Sell Stock IV LeetCode Solution

Problem Statement

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: i.e. you may buy at most k times and sell at most k times.

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.

Best Time to Buy and Sell Stock IV LeetCode Solution C++

class Solution {
public:
    int maxProfit(int k, vector<int>& prices) {
  
        vector<int> profits;
        stack<pair<int, int>> vps;
        
        int v;
        int p = -1;
        for (;;) {
            for (v = p+1; (v+1 < prices.size()) && (prices[v] >= prices[v+1]); ++v);
            for (p = v  ; (p+1 < prices.size()) && (prices[p] <= prices[p+1]); ++p);
            if (v == p) {
                break;
            }
            while ((!vps.empty()) && (prices[v] <= prices[vps.top().first])) {
                profits.push_back(prices[vps.top().second] - prices[vps.top().first]);
                vps.pop();
            }
            while ((!vps.empty()) && (prices[p] >= prices[vps.top().second])) {
                profits.push_back(prices[vps.top().second] - prices[v]);
                v = vps.top().first;
                vps.pop();
            }
            vps.emplace(v, p);
        }
        while (!vps.empty()) {
            profits.push_back(prices[vps.top().second] - prices[vps.top().first]);
            vps.pop();
        }

        int ret;
        if (profits.size() <= k) {
            ret = accumulate(profits.begin(), profits.end(), 0);
        } else {
            nth_element(profits.begin(), profits.end() - k, profits.end());
            ret = accumulate(profits.end() - k, profits.end(), 0);
        }
        return ret;
    }
};Code language: PHP (php)

Best Time to Buy and Sell Stock IV LeetCode Solution Java

class Solution {
public int maxProfit(int k, int[] prices) {
	int n = prices.length;
	if (n <= 1)
		return 0;
	if (k >=  n/2) {
		int maxPro = 0;
		for (int i = 1; i < n; i++) {
			if (prices[i] > prices[i-1])
				maxPro += prices[i] - prices[i-1];
		}
		return maxPro;
	}
	
    int[][] dp = new int[k+1][n];
    for (int i = 1; i <= k; i++) {
    	int localMax = dp[i-1][0] - prices[0];
    	for (int j = 1; j < n; j++) {
    		dp[i][j] = Math.max(dp[i][j-1],  prices[j] + localMax);
    		localMax = Math.max(localMax, dp[i-1][j] - prices[j]);
    	}
    }
    return dp[k][n-1];
}
}Code language: JavaScript (javascript)

Best Time to Buy and Sell Stock IV LeetCode Solution JavaScript

var maxProfit = function(k, prices) {
    if(prices.length == 0) return 0;
    if(k > (prices.length / 2) ){
        let profit = 0;
        for(let i = 1; i < prices.length; i++){
            if(prices[i] > prices[i - 1]){
                profit += prices[i] - prices[i - 1];
            }
        }
        return profit;
    }
    else{
        let dp = new Array(prices.length).fill(0);
        let size = prices.length;
        for(let t = 1; t <= k; t++){
            let min = prices[0];
            let max = 0;
            for(let i = 0; i < size; i++){
                min = Math.min(min, prices[i] - dp[i]);
                max = Math.max(max, prices[i] - min);
                dp[i] = max
            }
        }
        return dp.pop();   
    }
};Code language: JavaScript (javascript)

Best Time to Buy and Sell Stock IV LeetCode Solution Python

class Solution(object):
    def maxProfit(self, k, prices):
        if k == 0: return 0
        dp = [[1000, 0] for _ in range(k + 1)]
        for price in prices:
            for i in range(1, k + 1):
                dp[i][0] = min(dp[i][0], price - dp[i - 1][1])
                dp[i][1] = max(dp[i][1], price - dp[i][0])
        return dp[k][1]