Given an integer array nums, find the contiguous subarray within an array (containing at least one number) which has the largest product.

Example 1:

Input: [2,3,-2,4]
Output: 6
Explanation: [2,3] has the largest product 6.
Example 2:

Input: [-2,0,-1]
Output: 0
Explanation: The result cannot be 2, because [-2,-1] is not a subarray.

public int maxProduct(int[] nums) {
        int r = nums[0];
        int imax = nums[0];   //記錄包括當前數為結尾的連續子陣列的最大值
        int imin = nums[0];	//記錄包括當前數為結尾的連續子陣列的最小值
        for(int i = 1; i < nums.length; i++){
            if(nums[i] < 0){
                int tmp = imax;
                imax = imin;
                imin = tmp;
            }
            imax = Math.max(nums[i], nums[i] * imax);
            imin = Math.min(nums[i], nums[i] * imin);
            r = Math.max(r, imax);
        }
        return r;
    }