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.

贪心法 拿最大的卖出值减去最小的买入值（在卖出之前）

public class Solution {
	public int maxProfit(int[] prices) {
		if(prices.length<2) return 0;
		int sell = prices[0];
		int res = 0;
		for(int i=1;i<prices.length;i++){
			res = Math.max(res, prices[i]-sell);
			sell = Math.min(sell, prices[i]);
		}
		return res;
	}
}

[LeetCode]Best Time to Buy and Sell Stock