C++ map doubt

1

Hello , can any one please explain how to get the value of key of type pair<int,int> .
i.e map<pair<int,int>,int> ? I am getting an error
And also can anyone please explain when to use map and unordered_map ?

Thanks in advance

2

These should help you:

Retrieving keys or values from map

C++ Map vs. Unordered Map

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3

you need to define a hash function in unordered_map when you use pairs

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4

you can access the value like this-
map<pair<int,int>,int>mp;
cout<<mp[{x,y}];
where {x,y} is the pair

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5

or use auto :man_shrugging:

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6

Yeah , i was using unordered_map . Thanks btw !!

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7

You might also want to go through this article. It’s also gonna help if you don’t want to get hacked in CodeForces competitions. In fact, quite a few participants (including me) got their asses handed to them in this contest, in this problem for using unordered_map / unordered_set’s default hash function. :slightly_smiling_face:

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8

That was a really cool article; thanks!

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9

Thanks a lot bro ! :slight_smile:

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