LeetCode : 628. Maximum Product of Three Numbers

[congr]

https://leetcode.com/problems/maximum-product-of-three-numbers/

[congr]

NLogN

class Solution {
    public int maximumProduct(int[] nums) {
        Arrays.sort(nums);

        int N = nums.length - 1;
        int a = nums[0] * nums[1] * nums[N];
        int b = nums[N] * nums[N-1] * nums[N-2];

        return Math.max (a, b);
    }
}

[congr]

O(N)

class Solution {
    public int maximumProduct(int[] nums) {
        int min1 = Integer.MAX_VALUE, min2 = min1;
        int max1 = Integer.MIN_VALUE, max2 = max1, max3 = max1;

        for (int n : nums) {
            // find 2 smallest numbers
            if (n < min1) {
                min2 = min1; // min1 : smallest
                min1 = n;
            } else if (n < min2) {
                min2 = n;
            } 

            // find 3 largest numbers
            if (n > max3) { // max3 : largest
                max1 = max2;
                max2 = max3;
                max3 = n;
            } else if (n > max2) {
                max1 = max2;
                max2 = n;
            } else if (n > max1) {
                max1 = n;
            }
        }

        int a = min1 * min2 * max3;
        int b = max1 * max2 * max3;

        return Math.max (a, b);
    }
}