【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。

 1 class Solution {
 2 public:
 3     int maxProduct(int A[], int n) {
 4         
 5         int max_ending_here = A[0];
 6         int min_ending_here = A[0];
 7         
 8         int max_so_far = A[0];
 9         
10         for (int i = 1; i < n; ++i) {
11             int p_max = A[i] * max_ending_here;
12             int p_min = A[i] * min_ending_here;
13             
14             max_ending_here = max(A[i], max(p_max, p_min));
15             min_ending_here = min(A[i], min(p_max, p_min));
16             
17             max_so_far = max(max_so_far, max_ending_here);
18         }
19         
20         return max_so_far;
21     }
22 };