unordered_multimap count() function in C++ STL
The unordered_multimap::count() is a built-in function in C++ STL that returns the number of elements in the container whose key is equal to the key passed in the parameter. Syntax:
unordered_multimap_name.count(key)
Parameters: The function accepts a single mandatory parameter key that specifies the key whose count in the unordered_multimap container is to be returned. Return Value: It returns an unsigned integral type which denotes the number of times a key occurs in the container.
Time Complexity: O(N)
Below programs illustrates the above function: Program 1:
CPP
// C++ program to illustrate the // unordered_multimap::count() #include <bits/stdc++.h> using namespace std; int main() { // declaration unordered_multimap< int , int > sample; // inserts key and element sample.insert({ 10, 100 }); sample.insert({ 10, 100 }); sample.insert({ 20, 200 }); sample.insert({ 30, 300 }); sample.insert({ 30, 150 }); cout << "10 occurs " << sample.count(10) << " times" ; cout << "\n20 occurs " << sample.count(20) << " times" ; cout << "\n13 occurs " << sample.count(13) << " times" ; cout << "\n30 occurs " << sample.count(30) << " times" ; return 0; } |
Output:
10 occurs 2 times 20 occurs 1 times 13 occurs 0 times 30 occurs 2 times
Program 2:
CPP
// C++ program to illustrate the // unordered_multimap::count() #include <bits/stdc++.h> using namespace std; int main() { // declaration unordered_multimap< char , char > sample; // inserts key and element sample.insert({ 'a' , 'b' }); sample.insert({ 'a' , 'b' }); sample.insert({ 'b' , 'c' }); sample.insert({ 'r' , 'a' }); sample.insert({ 'r' , 'b' }); cout << "a occurs " << sample.count( 'a' ) << " times" ; cout << "\nb occurs " << sample.count( 'b' ) << " times" ; cout << "\nz occurs " << sample.count( 'z' ) << " times" ; cout << "\nr occurs " << sample.count( 'r' ) << " times" ; return 0; } |
Output:
a occurs 2 times b occurs 1 times z occurs 0 times r occurs 2 times
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