1 | #include "avl.h" |
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2 | #include "avl-private.h" |
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3 | |
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4 | forall(K | Comparable(K), V) |
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5 | V * find(tree(K, V) * t, K key){ |
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6 | if (empty(t)){ |
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7 | return NULL; |
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8 | } |
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9 | |
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10 | if (t->key == key){ |
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11 | return &t->value; |
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12 | } else if (t->key < key){ |
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13 | return find(t->right, key); |
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14 | } else { |
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15 | // t->key > key |
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16 | return find(t->left, key); |
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17 | } |
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18 | } |
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19 | |
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20 | forall(K | Comparable(K), V) |
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21 | int empty(tree(K, V) * t){ |
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22 | return t == NULL; |
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23 | } |
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24 | |
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25 | // returns the root of the tree |
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26 | forall(K | Comparable(K), V) |
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27 | int insert(tree(K, V) ** t, K key, V value) { |
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28 | // handles a non-empty tree |
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29 | // problem if the following signature is used: tries to use an adapter to call helper, but shouldn't |
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30 | // be necessary - seems to be a problem with helper's type variables not being renamed |
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31 | // tree(K, V) * helper(tree(K, V) * t, K key, V value){ |
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32 | tree(K, V) * helper(tree(K, V) * t){ |
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33 | if (t->key == key){ |
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34 | // ran into the same key - uh-oh |
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35 | return NULL; |
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36 | } else if (t->key < key){ |
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37 | if (t->right == NULL){ |
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38 | t->right = create(key, value); |
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39 | tree(K, V) * right = t->right; // FIX ME! |
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40 | right->parent = t; // !!!!!!! |
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41 | return t->right; |
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42 | } else { |
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43 | return helper(t->right); |
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44 | } |
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45 | } else { |
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46 | if (t->left == NULL){ |
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47 | t->left = create(key, value); |
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48 | tree(K, V) * left = t->left; // FIX ME! |
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49 | left->parent = t; // !!!!!!! |
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50 | return t->left; |
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51 | } else { |
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52 | return helper(t->left); |
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53 | } |
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54 | } |
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55 | } |
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56 | |
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57 | if (empty(*t)){ |
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58 | // be nice and return a new tree |
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59 | *t = create(key, value); |
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60 | return 0; |
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61 | } |
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62 | tree(K, V) * newTree = helper(*t); |
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63 | if (newTree == NULL){ |
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64 | // insert error handling code, only possibility |
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65 | // currently is that the key already exists |
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66 | return 99; |
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67 | } |
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68 | // move up the tree, updating balance factors |
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69 | // if the balance factor is -1, 0, or 1 keep going |
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70 | // if the balance factor is -2 or 2, call fix |
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71 | while (newTree->parent != NULL){ // loop until newTree == NULL? |
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72 | newTree = tryFix(newTree); |
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73 | tree(K, V) * parent = newTree->parent; // FIX ME!! |
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74 | assert(parent->left == newTree || |
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75 | parent->right == newTree); |
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76 | newTree = newTree->parent; |
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77 | } |
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78 | insert(t, key, value); |
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79 | |
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80 | // do it one more time - this is the root |
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81 | newTree = tryFix(newTree); |
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82 | *t = newTree; |
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83 | return 0; |
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84 | } |
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