Algorithm to Reverse a Singly-Linked List in C++

reverse-a-singly-linked-list.cpp

#include <iostream>
using namespace std;

struct node;

node * const NIL = (node * const) 0;

struct node {
    int value;
    node *next;
    node(int value) : value(value), next(NIL) {}
    node(int value, node *next) : value(value), next(next) {}
    ~node() { if (next) delete next; }
};

node *reverse(node *n) {
    node *h = NIL;
    while (n != NIL) {
        node *t = n->next;
        n->next = h;
        h = n;
        n = t;
    }
    return h;
}

void print(node *n) {
    cout << "[";
    while (n != NIL) {
        cout << n->value;
        if (n->next != NIL) {
            cout << ", ";
        }
        n = n->next;
    }
    cout << "]" << endl;
}

int main() {
    node *r;
    r = reverse(NIL);
    print(r); delete r;                                                     // []
    r = reverse(new node(1));
    print(r); delete r;                                                     // [1]
    r = reverse(new node(1, new node(2)));
    print(r); delete r;                                                     // [2, 1]
    r = reverse(new node(1, new node(2, new node(3))));
    print(r); delete r;                                                     // [3, 2, 1]
    r = reverse(new node(1, new node(2, new node(3, new node(4)))));
    print(r); delete r;                                                     // [4, 3, 2, 1]
    return 0;
}