Вектор!

std::vector<int> vec = {7, 4, 3, 1, 6};
std::cout << *std::max_element(vec.begin(), vec.end());

#include <vector>
#include <iostream>
#include <cmath>
#include <iterator>
 
int main(){
  std::vector<int> vec = {7, 4, 3, 1, 6};
  const int a = 5, b = 10, sz = vec.size();
  for(auto it = vec.begin(); it != vec.end(); ++it)
    if( abs(*it) >= a && abs(*it) <= b )
      vec.erase(it--);
  vec.insert(vec.end(), sz - vec.size(), 0);
  for(auto it = vec.begin(); it != vec.end(); ++it)
    std::cout << *it << ' ';
  return 0;
}

#include<iostream>
#include<numeric>
#include<algorithm>
#include<vector>
 
int main(){
    std::vector<int> con{1, 5, -7, -19, -6, -4, 0, -6};
    auto rit=std::find_if(con.rbegin(), con.rend(), [](int x){return x>0;});
    if(rit!=con.rend()&&rit!=--con.rend()){
        std::cout<<"Last positive= "<<*rit<<"\n";
        std::cout<<"sum= "<<std::accumulate(rit+1, con.rend(), 0);
    }
}