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.
解题：
遍历数组，随时记录当前出现过的最小值，和出现过的最大收益；
代码：
class Solution {
public:
int maxProfit(vector<int> &prices) {
int size = prices.size();
int minV = INT_MAX;
int maxP = ;
for (int i = ; i < size; ++i) {
minV = min(minV, prices[i]);
maxP = max(maxP, prices[i] - minV);
}
return maxP;
}
};