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：利用动态规划思想，记录到每个数截止时的最大值和最小值，用来推导下一个数的最大值和最小值；

代码：

1. int maxProduct(int A[], int n) {
2. if(n==0) return 0;
3. if(n==1) return A[0];
4. int max_here_val = A[0];
5. int min_here_val = A[0];
6. int max_val = A[0];
7. for(int i=1;i<n;i++) {
8. int tmp = max_here_val;
9. max_here_val = max(max(max_here_val * A[i],A[i]),min_here_val * A[i]); // the max value of current
10. min_here_val = min(min(A[i],tmp * A[i]),min_here_val * A[i]); //the min value of current
11. if(max_here_val > max_val) {
12. max_val = max_here_val;
13. }
14. }
15. return max_val;
16. }