C++ unordered set PMR解Leetcode 874 Walking Robot Simulation
解Leetcode 874. Walking Robot Simulation因為constraints，只好用hashmap，C++ unordered_set是知名的慢，加上pmr可以快上幾倍
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Solving LeetCode 874, Walking Robot Simulation, requires using a hashmap due to constraints. C++'s unordered_set is notoriously slow; adding PMR can speed it up several times.