Solution: Random Pick with Weight
Explore how to implement weighted random selection using running sums and modified binary search. Understand how to preprocess weights for efficient queries and apply binary search to select indices proportionally to their weights, optimizing time complexity.
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: ...