Random Pick with Weight

Understand how to perform weighted random selection from an array by implementing a Pick Index() function that chooses indices based on their weights. Explore the use of modified binary search to efficiently handle weighted probabilities and improve your coding interview skills.

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Statement

You’re given an array of positive integers, weights, where weights[i] is the weight of the $i^{th}$ index.

Write a function, Pick Index(), which performs weighted random selection to return an index from the weights array. The larger the value of weights[i], the heavier the weight is, and the higher the chances of its index being picked.

Suppose that the array consists of the weights $[12, 84, 35]$ . In this case, the probabilities of picking the indexes will be as follows:

Index 0: $12 / (12 + 84 + 35$ ...