Lista ordenada sem cabeça utilizando a recursão com elo.

lista_elo.cpp

#include <iostream>

struct snode{
    int value;
    snode * next;
    snode(int v = 0, snode * n = nullptr){
        value = v;
        next = n;
    }
};

//lista simples ordenada e sem cabeca
struct lista{
    snode * head;
    lista(){
        head = nullptr;
    }
    
    ~lista(){
        clear(head);
        head = nullptr;
    }
    
    void _insert(snode * node, int value, snode **elo){
        if(node == nullptr){
            *elo = new snode(value);
            return;
        }
        if(node->value > value){
            *elo = new snode(value, node);
            return;
        }
        _insert(node->next, value, &node->next);
    }
    
    void _pback(snode * node, int value, snode **elo){
        if(node == nullptr){
            *elo = new snode(value);
            return;
        }
        _pback(node->next, value, &node->next);
    }
    
    void _remove(snode * node, int value, snode ** elo){
        if(node == nullptr)
            return;
        _remove(node->next, value, &node->next);
        if(node->value == value){
            *elo = node->next;
            delete node;
            return;
        }
    }
    
    //retorna o elo do no
    //ou onde ele deveria estar
    snode ** _find_elo(snode * node, int value, snode ** elo){
        if(node == nullptr)
            return elo;
        if(node->value >= value)
            return elo;
        
        return _find_elo(node->next, value, &node->next);
    }
    
    snode ** find_elo(int value){
        return _find_elo(head, value, &head);
    }
    
    bool exist(int value){
        auto elo = find_elo(value);
        auto node = *elo;
        return (node != nullptr & node->value == value);
    }
     
    void new_insert(int value){
        auto elo = find_elo(value);
        *elo = new snode(value, *elo);
    }
    
    void insert(int value){
        _insert(head, value, &head);
    }
    
    
    void clear(snode * node){
        if(node == nullptr)
            return;
        clear(node->next);
        delete(node);
    }
    
    void _show(snode * node){
        if(node == nullptr)
            return;
        cout << node->value << " ";
        _show(node->next);
    }
    void show(){
        cout << "[ ";
        _show(head);
        cout << " ]";
    }
};