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letter.c
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letter.c
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//
// letter.c
// AsciiGenerator
//
// Created by Amy Dyer on 6/4/12.
// Copyright (c) 2012 Amy Dyer. Do whatever you like with this.
//
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <string.h>
#import "letter.h"
void balanceNode(node_t * node);
void setLeftNode(node_t * parent, node_t * leaf);
void setRightNode(node_t * parent, node_t * leaf);
node_t * findNode(node_t * root, float darkness, float diff);
void testNode(node_t * node);
#pragma mark - Tree creation and navigation
void insertLetter(node_t * root, char * character, float darkness)
{
float rootDarkness = root->letter->darkness;
if (strcmp(root->letter->character, character) == 0) {
return;
}
if (darkness < rootDarkness) {
if (root->left == NULL) {
node_t * n = newNode(character, darkness);
setLeftNode(root, n);
balanceNode(root->parent);
} else {
insertLetter(root->left, character, darkness);
}
} else {
if (root->right == NULL) {
node_t * n = newNode(character, darkness);
setRightNode(root, n);
balanceNode(root->parent);
} else {
insertLetter(root->right, character, darkness);
}
}
}
static char * characterAtNode(node_t * node)
{
if (node == NULL) return "";
return node->letter->character;
}
node_t * newNode(char * character, float darkness)
{
node_t * newNode = malloc(sizeof(node_t));
letter_t * newLetter = malloc(sizeof(letter_t));
newLetter->character = malloc(sizeof(character));
strcpy(newLetter->character, character);
newLetter->darkness = darkness;
newNode->letter = newLetter;
newNode->left = NULL;
newNode->right = NULL;
newNode->parent = NULL;
return newNode;
}
void setLeftNode(node_t * parent, node_t * leaf)
{
if (leaf != NULL) leaf->parent = parent;
if (parent != NULL) parent->left = leaf;
}
void setRightNode(node_t * parent, node_t * leaf)
{
if (leaf != NULL) leaf->parent = parent;
if (parent != NULL) parent->right = leaf;
}
static void destroyNode(node_t * node)
{
if (node == NULL) return;
free(node->letter->character);
free(node->letter);
free(node);
}
void destroyTree(node_t * root)
{
if (root == NULL) return;
destroyTree(root->left);
root->left = NULL;
destroyTree(root->right);
root->right = NULL;
destroyNode(root);
}
#pragma mark - Debug
void testNode(node_t * node)
{
if (node == NULL) return;
assert(node != node->parent);
assert(node != node->left);
assert(node != node->right);
assert(node == treeRoot ||
((node->parent->left == node) || (node->parent->right == node)));
assert(node->left != node->parent || (node->left == NULL && node->parent == NULL));
assert(node->right != node->parent || (node->right == NULL && node->parent == NULL));
assert((node->left != node->right) || (node->left == NULL && node->right == NULL));
}
static void printNode(node_t * node) {
if (node == NULL) return;
printNode(node->left);
printNode(node->right);
printf("<%s> parent: \"%s\" left: \"%s\" right: \"%s\"\n", characterAtNode(node), characterAtNode(node->parent), characterAtNode(node->left), characterAtNode(node->right));
}
void printTree()
{
printf("\n");
printNode(treeRoot);
printf("\n");
}
#pragma mark - AVL tree balancing
static void rotateRight(node_t * node)
{
node_t * newRoot = node->left;
node_t * oldRightChild= newRoot->right;
node_t * parent = node->parent;
if (node == treeRoot) {
treeRoot = newRoot;
}
setRightNode(newRoot, node);
setLeftNode(node, oldRightChild);
if (parent) {
if (parent->left == node) {
setLeftNode(parent, newRoot);
} else if (parent->right == node) {
setRightNode(parent, newRoot);
}
} else {
newRoot->parent = NULL;
}
}
static void rotateLeft(node_t * node)
{
node_t * newRoot = node->right;
node_t * oldLeftChild= newRoot->left;
node_t * parent = node->parent;
if (node == treeRoot) {
treeRoot = newRoot;
}
setLeftNode(newRoot, node);
setRightNode(node, oldLeftChild);
if (parent) {
if (parent->left == node) {
setLeftNode(parent, newRoot);
} else if (parent->right == node) {
setRightNode(parent, newRoot);
}
} else {
newRoot->parent = NULL;
}
}
static int maxChildHeight(node_t * root)
{
if (root == NULL)
return 0;
int leftHeight = maxChildHeight(root->left);
int rightheight = maxChildHeight(root->right);
return (leftHeight > rightheight? leftHeight : rightheight) + 1;
}
static int balanceFactor(node_t * root)
{
if (root == NULL) {
return 0;
}
int rightHeight = maxChildHeight(root->right);
int leftHeight = maxChildHeight(root->left);
return (leftHeight - rightHeight);
}
void balanceNode(node_t * node)
{
if (node == NULL)
return;
int diff = balanceFactor(node);
if (abs(diff) > 1) {
switch (diff) {
case -2:;
int rightBal = balanceFactor(node->right);
if (rightBal == -1) {
rotateLeft(node);
}
else if (rightBal == 1) {
rotateRight(node->right);
rotateLeft(node);
}
break;
case 2:;
int leftBal = balanceFactor(node->left);
if (leftBal == 1) {
rotateRight(node);
}
else if (leftBal == -1) {
rotateLeft(node->left);
rotateRight(node);
}
break;
default:
printf("Unbalanced: %i\n", diff);
}
}
balanceNode(node->parent);
}
#pragma mark - Search
node_t * findNode(node_t * root, float darkness, float diff)
{
if (!root) {
return NULL;
}
float nodeDarkness = root->letter->darkness;
float matchedDarkness = nodeDarkness > darkness ? nodeDarkness - darkness : darkness - nodeDarkness; //How close of a match it is
if (diff < matchedDarkness) {
//This node is actually less of a match than the previous node.
return NULL;
}
if (darkness < nodeDarkness) {
node_t * found = findNode(root->left, darkness, matchedDarkness);
return found ? found : root;
} else {
node_t * found = findNode(root->right, darkness, matchedDarkness);
return found ? found : root;
}
}
char * findLetter(node_t * root, float darkness)
{
node_t * node = findNode(root, darkness, 100000);
return node->letter->character;
}