Question

How to sort a vector of pairs based on the first element of the pair in descending order with C++

Answer 1

#include <algorithm>
#include <iostream>
#include <vector>

void print(const std::vector<std::pair<int, int>> vec) {
    for (const auto& val : vec) {
        std::cout << val.first << ", " << val.second << std::endl;
    }
}

int main()
{
    std::vector<std::pair<int, int>> vec = { {3, 8}, {5, 2}, {-4, 7} };
    
    std::sort(vec.begin(), vec.end(), [](auto &left, auto &right) {
        return left.first > right.first;
    });

    print(vec);
}

  
  
/*
run:
  
5, 2
3, 8
-4, 7
  
*/

 

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