task3 initial

Author: proton

week4/priority-queues/task3/TASK.md

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+### Taxicab numbers
+
+A `taxicab` number is an integer that can be expressed as the sum of two cubes of positive integers in two different ways: `a^3 + b^3 = c^3 + d^3`.
+For example, `1729` is the smallest taxicab number: `9^3 + 10^3 = 1^3 + 12^3`.
+Design an algorithm to find all taxicab numbers with `a`, `b`, `c`, and `d` less than `n`.
+
+- Version 1: Use time proportional to `(n^2)*log(n)` and space proportional to `n^2`.
+- Version 2: Use time proportional to `(n^2)*log(n)` and space proportional to `n`.