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  • 384. Shuffle an Array

    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();
    class Solution {
    
        private int[] arr;
        private Random generator;
        
        public Solution(int[] nums) {
            this.arr = new int[nums.length];
            this.generator = new Random(System.nanoTime());
            for (int i = 0; i < nums.length; i++) this.arr[i] = nums[i];
        }
        
        /** Resets the array to its original configuration and return it. */
        public int[] reset() {
            return arr;
        }
        
        /** Returns a random shuffling of the array. */
        public int[] shuffle() {
            int[] copy = new int[arr.length];
    
            int ind = 0;
            for (int i = 0; i < arr.length; i++) {
                while ((ind = generator.nextInt(arr.length)) < 0 || copy[ind] != 0) continue;
                copy[ind] = arr[i];
            }
            
            return copy;
        }
    }
    /**
     * Your Solution object will be instantiated and called as such:
     * Solution obj = new Solution(nums);
     * int[] param_1 = obj.reset();
     * int[] param_2 = obj.shuffle();
     */

    每次返回一个shuffle,就从0到arr.length,每个元素赋给新数组里的随机一个(这也叫shuffle?)

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  • 原文地址:https://www.cnblogs.com/wentiliangkaihua/p/11762645.html
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