# Java solution using K-transaction approach

• I took reference of other's solution and added some extra documentation for ease of understanding

``````    public int maxProfit(int[] prices) {
if(prices.length == 0){
return 0;
}

// this solution can be easily modified to solve k transaction problem
int transactions = 2;

// serives as a place holder to store the max possible profit for each sub problem
// rows represents stock price and the cols represents the transactions.
int[][] profitDP= new int[transactions + 1][prices.length];

// assuming we dont have any starting balance
int curBalance = 0;

for(int i = 1; i<=transactions; i++){

// since we cannot sell a stock before buying it so we can only buy the first day.
curBalance = profitDP[i-1][0] - prices[0];

for(int j=1; j<prices.length; j++){
// if we choose to sell we need to decide we need to decide if the prev balance (profitDB[i][j-1]) was more
// of updated balance (prices[j] + curBalance) is more. Since we will get price[j] if we sell on j'th day/
profitDP[i][j] = Math.max(profitDP[i][j - 1], prices[j] + curBalance);

// if we choose to buy then we need to decide if the updated balance (profitDP[i-1][j] - price[j]) is more or
// previous balance (curBalance) is more as we need to keep the buying cost to minimum
curBalance = Math.max(curBalance, profitDP[i-1][j] - prices[j]);
}
}

// max of each transactions
return Math.max(profitDP[transactions][prices.length - 1], profitDP[transactions - 1][prices.length - 1]);
}
``````

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