C++ :: Simple Tree But Pointers Changing Themselves

The code meant to generate a simple tree. As you can see from the output, somewhere the parent pointers get messed up. And yet, I can't seem to find where, and if I output them in the constructor (only time they get modified) they all look OK. When I run output_path_to_root() on any grandchildren of the root I get a segmentation fault. How the parents are getting messed up? I was wondering if my vectors changing size is causing pointers to shift around but I'm not sure.

//tree.cpp

#include <iostream>
#include <vector>
using namespace std;
struct A {
int n;
vector<A> get_children() {

[Code] .....

12 ( )
6 ( parent->node.n: 12)
3 ( parent->node.n: -1487162336)
1 ( parent->node.n: -1429198496)
2 ( parent->node.n: -1487162336)
1 ( parent->node.n: -1429198496)
4 ( parent->node.n: 12)
2 ( parent->node.n: -1487162336)
1 ( parent->node.n: -1429198496)