Doubt in Length of longest subarray with sum 0

#1

Please explain me line 18

#2

m.find(pre) != m.end()
it’s a STL function, what it does is if your .find(x) return end of m. Then it means that element is not present in unordered map. But if it returns any value other then that. Then the element x is present in unordered map.

#3

Thanks. I’m closing the doubt.

#4

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