[LeetCode]Shuffle an Array

用Fisher-Yates算法即可，时间复杂度O(n)，常数空间，代码如下：

	class Solution {
	public:
	Solution(vector<int> nums) {
	m_nums = nums;
	}
	/** Resets the array to its original configuration and return it. */
	vector<int> reset() {
	return m_nums;
	}
	/** Returns a random shuffling of the array. */
	vector<int> shuffle() {
	int len = m_nums.size();
	vector<int> res = m_nums;
	for(int i = len - 1; i >= 0; --i)
	{
	int random = rand() % (i + 1);
	swap(res[i], res[random]);
	}
	return res;
	}
	private:
	vector<int> m_nums;
	};
	/**
	* Your Solution object will be instantiated and called as such:
	* Solution obj = new Solution(nums);
	* vector<int> param_1 = obj.reset();
	* vector<int> param_2 = obj.shuffle();
	*/

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