Package g0301_0400.s0398_random_pick_index

Class Solution

java.lang.Object
g0301_0400.s0398_random_pick_index.Solution
public class Solution extends Object
398 - Random Pick Index\. Medium Given an integer array `nums` with possible **duplicates** , randomly output the index of a given `target` number. You can assume that the given target number must exist in the array. Implement the `Solution` class: * `Solution(int[] nums)` Initializes the object with the array `nums`. * `int pick(int target)` Picks a random index `i` from `nums` where `nums[i] == target`. If there are multiple valid i's, then each index should have an equal probability of returning. **Example 1:** **Input** ["Solution", "pick", "pick", "pick"] [[[1, 2, 3, 3, 3]], [3], [1], [3]] **Output:** [null, 4, 0, 2] **Explanation:** Solution solution = new Solution([1, 2, 3, 3, 3]); solution.pick(3); // It should return either index 2, 3, or 4 randomly. Each index should have equal probability of returning. solution.pick(1); // It should return 0. Since in the array only nums[0] is equal to 1. solution.pick(3); // It should return either index 2, 3, or 4 randomly. Each index should have equal probability of returning. **Constraints:** * 1 <= nums.length <= 2 * 104 * -231 <= nums[i] <= 231 - 1 * `target` is an integer from `nums`. * At most 104 calls will be made to `pick`.

  • Constructor Details

    • Solution

      public Solution(int[] nums)

  • Method Details

    • pick

      public int pick(int target)