628. Maximum Product of Three Numbers

Problem:

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:

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

思路：

Solution (C++):

int maximumProduct(vector<int>& nums) {
    sort(nums.begin(), nums.end());
    int n = nums.size();
    if (n < 3)  return 0;
    if (nums[n-1] > 0) {
        int max_two = max(nums[n-2]*nums[n-3], nums[0]*nums[1]);
        return nums[n-1] * max_two;
    } else {
        return nums[n-1] * nums[n-2] * nums[n-3];
    }
    return 0;
}

性能：

Runtime: 96 ms  Memory Usage: 8.8 MB

思路：

Solution (C++):

性能：

Runtime: ms  Memory Usage: MB