leetCode-Maximum Product of Three Numbers

Description:
Given an integer array, find three numbers whose product is maximum and output the maximum product.

Example 1:

Input: [1,2,3]
Output: 6

Example 2:

Input: [1,2,3,4]
Output: 24

Note:

    The length of the given array will be in range [3,104] and all elements are in the range [-1000, 1000].
    Multiplication of any three numbers in the input won't exceed the range of 32-bit signed integer.

Solution:

class Solution {
        public int maximumProduct(int[] nums) {
        int max1 = Integer.MIN_VALUE, max2 = Integer.MIN_VALUE, max3 = Integer.MIN_VALUE, min1 = Integer.MAX_VALUE, min2 = Integer.MAX_VALUE;
        //这段求最大三个数的代码很巧妙
        for (int n : nums) {
            if (n > max1) {
                max3 = max2;
                max2 = max1;
                max1 = n;
            } else if (n > max2) {
                max3 = max2;
                max2 = n;
            } else if (n > max3) {
                max3 = n;
            }

            if (n < min1) {
                min2 = min1;
                min1 = n;
            } else if (n < min2) {
                min2 = n;
            }
        }
        return Math.max(max1*max2*max3, max1*min1*min2);
    }
}

总结:找出最大的三个数，最小的两个数，返回max(max1*max2*max3,max1*min1*min2)

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