[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.

思路：使用动态规划，维护两个变量，一个正数的最大值pmax,一个负数的最大值pmin。

class Solution {
public:
    int maxProduct(int A[], int n) {
        int pmax = A[0],pmin = A[0],ans = A[0];
        for(int i = 1;i < n;i ++){
            int tmax = A[i] * pmax;
            int tmin = A[i] * pmin;
            pmax = max(A[i],max(tmax,tmin));
            pmin = min(A[i],min(tmax,tmin));
            ans = max(ans,pmax);
        }
        return ans;
    }
};