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] <= 1000class Solution {
public:
int maxProfit(int k, vector<int> &prices) {
int len = prices.size();
if (len<2) return 0;
if (k>len/2){ // simple case
int ans = 0;
for (int i=1; i<len; ++i){
ans += max(prices[i] - prices[i-1],0);
}
return ans;
}
int hold[k+1];
int rele[k+1];
for (int i=0;i<=k;++i){
hold[i] = INT_MIN;
rele[i] = 0;
}
int cur;
for (int i=0; i<len; ++i){
cur = prices[i];
for(int j=k; j>0; --j){
rele[j] = max(rele[j],hold[j] + cur);
hold[j] = max(hold[j],rele[j-1] - cur);
}
}
return rele[k];
}
};