整型数组nums，在数组中找出由三个数字组成的最大乘积，并输出这个乘积。
    乘积不会越界

    1. public class MaxProduct {
    2.     public static void main(String[] args) {
    3.         System.out.println(sort(new int[]{1, 2, 3, 4, 5, 6}));
    4.         System.out.println(getMaxMin(new int[]{1, 2, 3, 4, 5, 6}));
    5.     }
    7.     private static int sort(int[] nums) {
    8.         Arrays.sort(nums);
    9.         int n = nums.length;
    10.         return Math.max(nums[0] * nums[1] * nums[n - 1], nums[n - 1] * nums[n - 2] * nums[n - 3]);
    11.     }
    13.     //线型扫描
    14.     public static int getMaxMin(int[] nums) {
    15.         int min1 = Integer.MAX_VALUE, min2 = Integer.MAX_VALUE;
    16.         int max1 = Integer.MIN_VALUE, max2 = Integer.MIN_VALUE, max3 = Integer.MIN_VALUE;
    17.         for (int num : nums) {
    18.             if (num < min1) {
    19.                 min2 = min1;
    20.                 min1 = num;
    21.             } else if (num < min2) {
    22.                 min2 = num;
    23.             }
    24.             if (num > max1) {
    25.                 max3 = max2;
    26.                 max2 = max1;
    27.                 max1 = num;
    28.             } else if (num > max2) {
    29.                 max3 = max2;
    30.                 max2 = num;
    31.             } else if (num > max3) {
    32.                 max3 = num;
    33.             }
    35.         }
    36.         return Math.max(min1 * min2 * max1, max1 * max2 * max3);
    37.     }
    38. }