Given an integer array nums
, design an algorithm to randomly shuffle the array. All permutations of the array should be equally likely as a result of the shuffling.
Implement the Solution
class:
Solution(int[] nums)
Initializes the object with the integer arraynums
.int[] reset()
Resets the array to its original configuration and returns it.int[] shuffle()
Returns a random shuffling of the array.
Example 1:
Input ["Solution", "shuffle", "reset", "shuffle"] [[[1, 2, 3]], [], [], []] Output [null, [3, 1, 2], [1, 2, 3], [1, 3, 2]] Explanation Solution solution = new Solution([1, 2, 3]); solution.shuffle(); // Shuffle the array [1,2,3] and return its result. // Any permutation of [1,2,3] must be equally likely to be returned. // Example: return [3, 1, 2] solution.reset(); // Resets the array back to its original configuration [1,2,3]. Return [1, 2, 3] solution.shuffle(); // Returns the random shuffling of array [1,2,3]. Example: return [1, 3, 2]
Constraints:
1 <= nums.length <= 50
-106 <= nums[i] <= 106
- All the elements of
nums
are unique. - At most
104
calls in total will be made toreset
andshuffle
.
A:
Fisher–Yates shuffle
class Solution { public: vector<int> v; Solution(vector<int>& nums) { v=nums; } vector<int> reset() { return v; } vector<int> shuffle() { vector<int> res = v; int random = rand(); for(int i =v.size()-1;i > 0;--i){ int newIdx = rand() % (i+1); if(newIdx != i){// swap if needed int tmp = res[i]; res[i] = res[newIdx]; res[newIdx] = tmp; } } return res; } }; /** * 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(); */
No comments:
Post a Comment