Class Solution
java.lang.Object
g0301_0400.s0398_random_pick_index.Solution
398 - Random Pick Index.<p>Medium</p>
<p>Given an integer array <code>nums</code> with possible <strong>duplicates</strong> , randomly output the index of a given <code>target</code> number. You can assume that the given target number must exist in the array.</p>
<p>Implement the <code>Solution</code> class:</p>
<ul>
<li><code>Solution(int[] nums)</code> Initializes the object with the array <code>nums</code>.</li>
<li><code>int pick(int target)</code> Picks a random index <code>i</code> from <code>nums</code> where <code>nums[i] == target</code>. If there are multiple valid i’s, then each index should have an equal probability of returning.</li>
</ul>
<p><strong>Example 1:</strong></p>
<p><strong>Input</strong></p>
<pre><code> ["Solution", "pick", "pick", "pick"]
[[[1, 2, 3, 3, 3]], [3], [1], [3]]
</code></pre>
<p><strong>Output:</strong> [null, 4, 0, 2]</p>
<p><strong>Explanation:</strong></p>
<pre><code> 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.
</code></pre>
<p><strong>Constraints:</strong></p>
<ul>
<li><code>1 <= nums.length <= 2 * 10<sup>4</sup></code></li>
<li><code>-2<sup>31</sup> <= nums[i] <= 2<sup>31</sup> - 1</code></li>
<li><code>target</code> is an integer from <code>nums</code>.</li>
<li>At most <code>10<sup>4</sup></code> calls will be made to <code>pick</code>.</li>
</ul>
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Constructor Summary
Constructors -
Method Summary
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Constructor Details
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Solution
public Solution(int[] nums)
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Method Details
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pick
public int pick(int target)
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