// 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();
class Solution {
public:
Solution(vector<int>& nums) : arr(nums) {
srand(time(NULL));
}
/** Resets the array to its original configuration and return it. */
vector<int> reset() {
return arr;
}
/** Returns a random shuffling of the array. */
vector<int> shuffle() {
vector<int> res = arr;
for (int i = 0; i < res.size(); ++i) {
// int j = i + rand() % (res.size() - i);
int j = rand() % (i + 1);
swap(res[i], res[j]);
}
return res;
}
private:
vector<int> arr;
};