152. Maximum Product Subarray

题目分析

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.

时间复杂度 O(n)，空间复杂度 O(1)。

代码

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