2) What is Blockchain?A blockchain is a distributed digital ledger that allows for the secure storage of data. By recording any kind of information—such as bank account transactions, the ownership of Non-Fungible Tokens (NFTs), or Decentralized Finance (DeFi) smart contracts—in one place, and distributing it to many different computers, blockchains ensure that data can’t be manipulated without everyone in the system being aware.
This is the moment a SpaceX capsule left the International Space Station on an emergency return flight to Earth prompted by a medical issue afflicting one of the astronauts. It is Nasa’s first medical evacuation, with the mission being cut a month short. Onboard were American astronauts Mike Fincke and Zena Cardman, a Russian cosmonaut Oleg Platonov, and a Japanese astronaut Kimiya Yui. Computer modelling predicted a medical evacuation from the space station every three years but Nasa has not had one before in its 65 years of human spaceflight
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Metro has been responding directly to riders on X from its @metrolosangeles account, leaning fully into the internet moment.
思路：先对 nums2 用单调栈求每个元素的下一个更大值，存入 Map 缓存；再遍历 nums1 直接查 Map 得结果。时间复杂度 O(len1 + len2)。