Problem - Best Time to Buy and Sell Stock II

Now you can make as many transactions as you want.

You can buy and sell on the same day, but you cannot hold multiple shares. For $prices = [7,1,5,3,6,4]$, the maximum profit is $7$: buy at $1$, sell at $5$ (profit $4$), buy at $3$, sell at $6$ (profit $3$).

With unlimited transactions, the greedy approach changes.

Think about when it makes sense to "buy" and when to "sell." Every upward price movement is profit.