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/*
Challenge 094
TASK #2 � Binary Tree to Linked List
Submitted by: Mohammad S Anwar
You are given a binary tree.
Write a script to represent the given binary tree as an object and flatten
it to a linked list object. Finally print the linked list object.
Example:
Input:
1
/ \
2 3
/ \
4 5
/ \
6 7
Output:
1 -> 2 -> 4 -> 5 -> 6 -> 7 -> 3
*/
#include <exception>
#include <stdexcept>
#include <iostream>
#include <string>
#include <vector>
#include <cctype>
// input image object
class InputImage {
public:
void append_line(const std::string& line);
void clear();
char ch(int row, int col) const;
int root_col() const;
private:
std::vector<std::string> m_lines;
};
void InputImage::append_line(const std::string& line) {
m_lines.push_back(line);
}
void InputImage::clear() {
m_lines.clear();
}
char InputImage::ch(int row, int col) const {
// check if out of bounds
if (row < 0 || row >= static_cast<int>(m_lines.size()) ||
col < 0 || col >= static_cast<int>(m_lines[row].size()))
return ' ';
else
return m_lines[row][col];
}
int InputImage::root_col() const {
if (m_lines.empty())
throw std::invalid_argument("malformed image");
for (int col = 0; col < static_cast<int>(m_lines[0].size()); col++) {
if (isdigit(m_lines[0][col]))
return col;
}
throw std::invalid_argument("malformed image");
}
// tree object
class Tree {
public:
Tree(int value = 0);
~Tree();
int value;
Tree* left, * right;
static Tree* parse(const InputImage& image);
static Tree* flatten(Tree* root);
private:
static Tree* parse_subtree(const InputImage& image, int row, int col);
};
Tree::Tree(int value_)
: value(value_), left(nullptr), right(nullptr)
{}
Tree::~Tree() {
if (left) delete left;
if (right) delete right;
}
Tree* Tree::parse(const InputImage& image) {
int col = image.root_col();
return parse_subtree(image, 0, col);
}
Tree* Tree::parse_subtree(const InputImage& image, int row, int col) {
// parse root
int value = image.ch(row, col) - '0';
if (value < 0 || value>9)
throw std::invalid_argument("malformed image");
Tree* node = new Tree(value);
// parse left subtree
if (image.ch(row + 1, col - 1) == '/')
node->left = parse_subtree(image, row + 2, col - 2);
// parse right subtree
if (image.ch(row + 1, col + 1) == '\\')
node->right = parse_subtree(image, row + 2, col + 2);
return node;
}
Tree* Tree::flatten(Tree* root) {
if (!root) return root;
Tree* left = flatten(root->left);
Tree* right = flatten(root->right);
root->left = NULL;
root->right = left;
Tree* node = root;
while (node->right) // find right-most node
node = node->right;
node->right = right;
return root;
}
// read input from stdin
void read_lines(InputImage& image) {
image.clear();
std::string line;
while (!std::getline(std::cin, line).eof())
image.append_line(line);
}
int main(int argc, char* argv[]) {
InputImage image;
read_lines(image);
Tree* tree = Tree::flatten(Tree::parse(image));
for (Tree* node = tree; node; node = node->right) {
if (node != tree)
std::cout << " -> ";
std::cout << node->value;
}
std::cout << std::endl;
delete tree;
}
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