628.maximum-product-of-three-numbers.java

/*
 * @lc app=leetcode id=628 lang=java
 *
 * [628] Maximum Product of Three Numbers
 */

// @lc code=start
class Solution {
    public int maximumProduct(int[] nums) {
        //Main idea: find top three maximum and top two minimum
        int min1 = Integer.MAX_VALUE;
        int min2 = Integer.MAX_VALUE;
        int max1 = Integer.MIN_VALUE;
        int max2 = Integer.MIN_VALUE;
        int max3 = Integer.MIN_VALUE;

        for (int num : nums) {
            //find top two minimum number
            if (num <= min1) {
                min2 = min1;
                min1 = num;
            } else if (num <= min2) {
                min2 = num;
            }
            //find top three maximum number
            if (num >= max1) {
                max3 = max2;
                max2 = max1;
                max1 = num;
            } else if (num >= max2) {
                max3 = max2;
                max2 = num;
            } else if (num >= max3) {
                max3 = num;
            }
        }
        return Math.max(min1 * min2 * max1, max1 * max2 * max3);
    }
}
// @lc code=end