152 Maximum Product Subarray

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.

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这题跟“最大连续子序列和”非常类似，只不过变成了“最大连续子序列积”，所以解决   思路也很类似。
仅仅有一个小细节需要注意，就是负负得正，两个负数的乘积是正数，因此我们不   仅要跟踪最大值，还要跟踪最小值

class Solution {
    public int maxProduct(int[] nums) {
        int maxLocal = nums[0];
        int minLocal = nums[0];
        int maxGlobal = nums[0];
        
        for (int i = 1; i < nums.length; i++) {
            int temp = maxLocal;
            maxLocal = Math.max(nums[i], Math.max(nums[i] * maxLocal, nums[i] * minLocal));
            minLocal = Math.min(nums[i], Math.min(nums[i] * temp, nums[i] * minLocal));
            maxGlobal = Math.max(maxLocal, maxGlobal);
        }
        
        return maxGlobal;
    }
}