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384. Shuffle an Array

384. Shuffle an Array

作者: a_void | 来源:发表于2016-09-28 23:06 被阅读0次

    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();
    

    Solution:

    class Solution {
    public:
        vector<int> v;
        int size;
        Solution(vector<int> nums) {
            v = nums;
            size = nums.size();
            srand(time(0));
        }
        
        /** Resets the array to its original configuration and return it. */
        vector<int> reset() {
            return v;
        }
        
        /** Returns a random shuffling of the array. */
        vector<int> shuffle() {
            vector<int> t(v);
            for(int i=0;i<size - 1;i++){
                int r = randomBetween(i, size-1);
                swap(t[i], t[r]);
            }
            return t;
        }
        
        inline void swap(int &a, int &b){
            int t = a;
            a = b;
            b = t;
        }
        
        int randomBetween(int a, int b){
            if(a == b) return a;
            if(a > b) return randomBetween(b, a);
            return rand() % (b-a+1) + a;
        }
    };
    
    /**
     * 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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