Solution: Random Pick with Weight
Understand how to perform weighted random selection by generating running sums and using modified binary search. Explore the method to select indices based on weight probabilities, improving time complexity from linear to logarithmic. This lesson guides you through implementing and optimizing the solution for interview coding challenges.
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:
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Index 2: ...