121. 买卖股票的最佳时机
class Solution {
public int maxProfit(int[] prices) {
if (prices == null || prices.length <= 1)
return 0;
int minPrices = prices[0];
int ans = 0;
for (int i = 1; i < prices.length; i++) {
if (prices[i] < minPrices)
minPrices = prices[i];
else if (ans < prices[i] - minPrices)
ans = prices[i] - minPrices;
}
return ans;
}
}