767. Reverse Array

Reverse the given array nums inplace.

Inplace means you can’t use extra space.

Have you met this question in a real interview?

Example
Example 1:

Input : nums = [1,2,5]
Output : [5,2,1]

解题思路：
双指针法 i, j, 分别从头尾向中间遍历，i < j 时交换数值。

不占用额外空间的交换：
a=a+b;
b=a-b;
a=a-b;

class Solution:
    """
    @param nums: a integer array
    @return: nothing
    """
    def reverseArray(self, nums):
        # write your code here
        i, j = 0, len(nums) - 1 
        while i < j:
            nums[i] = nums[i] + nums[j]
            nums[j] = nums[i] - nums[j]
            nums[i] = nums[i] - nums[j]
            i += 1
            j -= 1
        return nums