152. 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.

public class Solution {
    public int maxProduct(int[] nums) {
        if(nums==null || nums.length==0)
            return 0;
        int global = nums[0];
        int max_local = nums[0];
        int min_local = nums[0];
        for(int i=1;i<nums.length;i++)
        {
            int max_copy = max_local;
            max_local = Math.max(Math.max(nums[i],max_local*nums[i]),min_local*nums[i]);
            min_local = Math.min(Math.min(nums[i],max_copy*nums[i]),min_local*nums[i]);//维护一个最小值。负负得正
            global = Math.max(max_local,global);
        }
        return global;

    }
}