【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.

求连续子序列最大乘积，类似于求连续子序列最大和，但是乘法还涉及到符号的问题，比较方便的方法是同时维护到当前元素的最大乘积和最小乘积。

class Solution {
public:
    int maxProduct(int A[], int n) {
        
        int max_ending_here = A[0];
        int min_ending_here = A[0];
        
        int max_so_far = A[0];
        
        for (int i = 1; i < n; ++i) {
            int p_max = A[i] * max_ending_here;
            int p_min = A[i] * min_ending_here;
            
            max_ending_here = max(A[i], max(p_max, p_min));
            min_ending_here = min(A[i], min(p_max, p_min));
            
            max_so_far = max(max_so_far, max_ending_here);
        }
        
        return max_so_far;
    }
};