leetcode-lintcode/152_maximum_product_subarray.java at master · lt616/leetcode-lintcode · GitHub

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/*
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.
*/

class Solution {
    public int maxProduct(int[] nums) {
        int[] dp_max = new int[nums.length + 1];
        int[] dp_min = new int[nums.length + 1];
        dp_max[0] = 1;
        dp_min[0] = 1;

        int max_product = Integer.MIN_VALUE;
        for (int i = 1;i <= nums.length;i ++) {
            dp_max[i] = max(nums[i - 1], nums[i - 1] * dp_max[i - 1], nums[i - 1] * dp_min[i - 1]);
            max_product = (dp_max[i] > max_product) ? dp_max[i] : max_product;
            dp_min[i] = min(nums[i - 1], nums[i - 1] * dp_max[i - 1], nums[i - 1] * dp_min[i - 1]);
        }

        return max_product;
    }

    private int max(int a, int b, int c) {
        int temp = (a > b) ? a : b;
        return (temp > c) ? temp : c;
    }

    private int min(int a, int b, int c) {
        int temp = (a < b) ? a : b;
        return (temp < c) ? temp : c;
    }
}