384. Shuffle an Array

• Difficulty: Medium

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Problem:

Shuffle a set of numbers without duplicates.

Example:

// Init an array with set 1, 2, and 3.
int[] nums = {1,2,3};
Solution solution = new Solution(nums);

// Shuffle the array [1,2,3] and return its result. Any permutation of [1,2,3] must equally likely to be returned. solution.shuffle();

// Resets the array back to its original configuration [1,2,3]. solution.reset();

// Returns the random shuffling of array [1,2,3]. solution.shuffle(); </pre> </p>

Solutions:

class Solution {
public:
    Solution(vector<int>& nums) {
        this->nums = nums;
    }

    /** Resets the array to its original configuration and return it. */
    vector<int> reset() {
        return nums;
    }

    /** Returns a random shuffling of the array. */
    vector<int> shuffle() {
        vector<int> ret(nums.begin(), nums.end());
        for (int i = 0; i < ret.size(); ++i) {
            int pos = rand() % (ret.size() - i);
            swap(ret[i], ret[i + pos]);
        }
        return ret;
    }

private:
    vector<int> 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();
 */