• Best Time to Buy and Sell Stock I,II,III [leetcode]


    Best Time to Buy and Sell Stock I

    你只能一个操作:维修preMin拍摄前最少发生值

    代码例如以下:

        int maxProfit(vector<int> &prices) {
            if (prices.size() == 0) return 0;
            int profit = 0;
            int preMin = prices[0];
            for (int i = 1; i < prices.size(); i++)
            {
                if (prices[i] < preMin) preMin = prices[i];
                profit = max(profit, prices[i] - preMin);
            }
            return profit;
        }

    Best Time to Buy and Sell Stock II

    能无限次操作时:当==>当前价格 > 买入价格的时候,卖出

    代码例如以下:

        int maxProfit(vector<int> &prices) {
            if (prices.size() == 0) return 0;
            int profit = 0;
            int buy = prices[0];
            for (int i = 1; i < prices.size(); i++)
            {
                if (buy < prices[i])
                    profit += prices[i] - buy;
                buy = prices[i];
            }
            return profit;
        }

    Best Time to Buy and Sell Stock III

    仅仅能操作两次时:

    两次操作不能重叠。能够分成两部分:0...i的最大利润fst  和i...n-1的最大利润snd

    代码例如以下:

        int maxProfit(vector<int> &prices) {
            if (prices.size() == 0) return 0;
            int size = prices.size();
            vector<int> fst(size);
            vector<int> snd(size);
            
            int preMin = prices[0];
            for (int i = 1; i < size; i++)
            {
                if (preMin > prices[i]) preMin = prices[i];
                fst[i] = max(fst[i - 1], prices[i] - preMin);
            }
            int profit = fst[size - 1];
            int postMax = prices[size - 1];
            for (int i = size - 2; i >= 0; i--)
            {
                if (postMax < prices[i]) postMax = prices[i];
                snd[i] = max(snd[i + 1], postMax - prices[i]);
                //update profit
                profit = max(profit, snd[i] + fst[i]);
            }
            return profit;
        }


    版权声明:本文博主原创文章。博客,未经同意不得转载。

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  • 原文地址:https://www.cnblogs.com/blfshiye/p/4822956.html
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