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All leaked interview problems are collected from Internet.

All leaked interview problems are collected from Internet.

Given an array of integers 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.

**Note:**

The array size can be very large. Solution that uses too much extra space will not pass the judge.

**Example:**

int[] nums = new int[] {1,2,3,3,3}; Solution solution = new Solution(nums); // pick(3) should return either index 2, 3, or 4 randomly. Each index should have equal probability of returning. solution.pick(3); // pick(1) should return 0. Since in the array only nums[0] is equal to 1. solution.pick(1);

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