[LeetCode] Maximum Product Subarray

Find the contiguous subarray within an array (containing at least one number) which has the largest product.

For example, given the array [2,3,-2,4],
the contiguous subarray [2,3] has the largest product = 6.

 

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 Array Dynamic Programming

 

 

参考 http://www.cnblogs.com/diegodu/p/4589796.html

class Solution {
public:
    int maxProduct(vector<int>& arr) {

            if(arr.size() == 0)
                return 0;
            int minVal = arr[0];
            int maxVal = arr[0];
            int rtn = arr[0];
 
            int tmpMax = 0;
            int tmpMin = 0;
 
            for(int i = 1; i < arr.size(); i++)
            {  
                //cout << "max\t" << maxVal << endl;
                //cout << "min\t" << minVal << endl;
                tmpMax = max(maxVal * arr[i], minVal * arr[i]);
                tmpMin = min(maxVal * arr[i], minVal * arr[i]);
 
                maxVal = max(tmpMax, arr[i]);
                minVal = min(tmpMin, arr[i]);
 
                rtn = max(rtn, maxVal);
            }  
            return rtn;
        }  
};