# 13846 - Reconstruct swapped binary search trees
>author: Utin
###### tags: `binary tree`
---

## Brief
See the code below

## Solution 0

#include <stdio.h>
#include <stdlib.h>

typedef struct _node {
    long long value;
    struct _node* left, * right;
} Node;

Node* head = NULL;

Node* make_node(long long value);
void add_node(long long value, Node* ptr);
void print_tree_post(Node* ptr, int tail);

int main() {
    long long input, N;
    scanf("%lld", &N);
    for (int i = 0; i < N; i++) {
        scanf("%lld", &input);
        add_node(input, head);
    }
    print_tree_post(head, 1);
}

Node* make_node(long long value) {
    Node* new_node = (Node*) malloc(sizeof(Node));
    new_node->value = value;
    new_node->left = new_node->right = NULL;
    return new_node;
}

void add_node(long long value, Node* ptr) {
    if (!head) head = make_node(value);
    else {
        if (value <= ptr->value) {
            if (ptr->left) add_node(value, ptr->left);
            else ptr->left = make_node(value);
        }
        else {
            if (ptr->right) add_node(value, ptr->right);
            else ptr->right = make_node(value);
        }
    }
}

void print_tree_post(Node* ptr, int tail) {
    if (ptr->left) print_tree_post(ptr->left, 0);
    if (ptr->right) print_tree_post(ptr->right, 0);
    printf("%lld", ptr->value);
    tail ? printf("\n") : printf(" ");
}

// Utin

## Reference