Best Time to Buy and Sell Stock II

public class Solution {
    public int maxProfit(int[] prices) {
        // Note: The Solution object is instantiated only once and is reused by each test case.
        int profit = 0;
        int buy = 0;
        int sell = 0;
        int lastTran = 0;  //flag for tracking the transactions, '0' is sell, '1' is buy
        if(prices.length == 0 || prices.length == 1) return 0;  //empty array
        if(prices[0] < prices[1])   //cannot buy when equal as (2,2,5)
        {
          buy += prices[0];
          lastTran = 1;
        }
        for(int i=1; i<prices.length;i++)
        {
            if(i == prices.length-1)  //special case at the last element
            {
                if(lastTran == 1) sell += prices[i];
            }
            else if(prices[i-1]<=prices[i] && prices[i]>prices[i+1])  //top
            {
             if(lastTran == 1)          //check if bought before sell
              {
              sell += prices[i];
              lastTran = 0;
              }
            }
            else if(prices[i-1]>=prices[i] && prices[i]<prices[i+1])  //bottom
            {  
               if(lastTran == 0)       //check if sold before buy
               {
                buy += prices[i];
                lastTran = 1;
               }
            }
        }
        profit = sell - buy;
        return profit;
    }
}