lintcode-medium-Best Time to Buy and Sell Stock

Say you have an array for which the ith element is the price of a given stock on day i.

If you were only permitted to complete at most one transaction (ie, buy one and sell one share of the stock), design an algorithm to find the maximum profit.

Given an example [3,2,3,1,2], return 1.

 

这道题也是动态规划，用一个变量min记录前i天最低的价格，用profit记录到第i天最大利润

public class Solution {
    /**
     * @param prices: Given an integer array
     * @return: Maximum profit
     */
    public int maxProfit(int[] prices) {
        // write your code here
        if(prices == null || prices.length == 0)
            return 0;
        
        int min = prices[0];
        int profit = 0;
        
        for(int i = 1; i < prices.length; i++){
            if(prices[i] < min)
                min = prices[i];
            
            profit = Math.max(profit, prices[i] - min);
        }
        
        return profit;
    }
}