Leetcode 121. best time to Buy and Sell Stock array

121. Best time to Buy and Sell Stock

Say you has an array for which the i-th element is the price of a given-stock on day I.

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

Example 1:

Input: [7, 1, 5, 3, 6, 4]output:5max. difference = 6-1 = 5 (Not 7-1 = 6, as selling-price needs-be-larger than buying price)

Example 2:

Input: [7, 6, 4, 3, 1]output:0in this case, no transaction was done, i.e. Max Profit = 0.

Main topic:

In an array, the maximum value is obtained by subtracting the preceding element from the previous element and returning the maximum value.

Ideas:

You can use a double loop to come out, but the efficiency is too low. did not pass.

Take the minimum value before the current value, subtract the previous minimum value from the current one to get a temporary maximum value, traverse the entire array, and find the maximum value.

Class solution {public:    int maxprofit (vector<int>& prices )  {        if (Prices.size ()  <= 1)              return 0;         int max = 0;        int curMin =  Prices[0];                for ( Int i = 1;i<prices.size (); i++)         {             if (Prices[i] - curmin > max )                 max =  prices[i] - curmin;            if ( prices[i] &Lt; curmin)                  curMin = prices[i];        }         return max;    }};

2016-08-12 08:43:51

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Leetcode 121. best time to Buy and Sell Stock array