STL 函数

#include <iostream>
#include <vector>
#include <numeric>

int main() {
  int arr[] = { 2, 3, 4, 5, 6 };
  std::vector<int> v(arr, arr + 5);
  int sum = std::accumulate(v.begin(), v.end(), 0);
  std::cout << sum << std::endl;
}