Q:
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();
A:
***********首先要有个nums的备份, 然后每次返回的时候,要一个shuffle的备份 *******
public class Solution {
private static int[] A;
private int[] B;
public Solution(int[] nums) {
A = nums;
B = new int[A.length];
for(int i = 0;i<A.length;i++)
B[i] = A[i];
}
/** Resets the array to its original configuration and return it. */
public int[] reset() {
for(int i = 0;i<A.length;i++)
B[i] = A[i];
return B;
}
/** Returns a random shuffling of the array. */
public int[] shuffle() {
for(int i =B.length-1;i>0;i--){
int j = (int)(Math.random()*(i+1));
int tmp = B[i];
B[i] = B[j];
B[j] = tmp;
}
return B;
}
}
/**
* 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();
*/
Errors:
public class Solution { private static int[] A; private int[] B; public Solution(int[] nums) { A = nums; B = new int[A.length]; for(int i = 0;i<A.length;i++) B[i] = A[i]; } /** Resets the array to its original configuration and return it. */ public int[] reset() { for(int i = 0;i<A.length;i++) B[i] = A[i]; return B; } /** Returns a random shuffling of the array. */ public int[] shuffle() { for(int i =B.length-1;i>0;i--){ int j = (int)(Math.random()*(i+1)); int tmp = B[i]; B[i] = B[j]; B[j] = tmp; } return B; } } /** * 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(); */
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