Solution: Random Pick with Weight
Understand how to perform weighted random selection by transforming weights into running sums and using binary search to pick indexes proportionally to their weight. This lesson helps improve efficiency from a linear to logarithmic time solution and is valuable for coding interviews involving probabilistic selections.
Statement
You’re given an array of positive integers, weights, where weights[i] is the weight of the 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 . In this case, the probabilities of picking the indexes will be as follows:
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Index 0:
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Index 1: ...