Payments & fintechMediumSDE-1

A wallet has ₹1,000. Two requests to spend ₹700 arrive at the same millisecond on different servers. How do you make sure the wallet never goes negative?

Asked at

AmazonPaytmPhonePe

Think first

Answer out loud as you would in the room — clarify, give numbers, name the trade-off — then compare with the model answer.

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