|
| 1 | + |
| 2 | +const Compare = { |
| 3 | + LESS_THAN: -1, |
| 4 | + BIGGER_THAN: 1, |
| 5 | + EQUALS: 0 |
| 6 | +}; |
| 7 | + |
| 8 | +function defaultCompare(a, b) { |
| 9 | + if (a === b) { |
| 10 | + return Compare.EQUALS; |
| 11 | + } |
| 12 | + return a < b ? Compare.LESS_THAN : Compare.BIGGER_THAN; |
| 13 | +} |
| 14 | +class Node { |
| 15 | + constructor(key) { |
| 16 | + this.key = key; |
| 17 | + this.left = undefined; |
| 18 | + this.right = undefined; |
| 19 | + } |
| 20 | + |
| 21 | + toString() { |
| 22 | + return `${this.key}`; |
| 23 | + } |
| 24 | +} |
| 25 | +class BinarySearchTree { |
| 26 | + constructor(compareFn = defaultCompare) { |
| 27 | + this.compareFn = compareFn; |
| 28 | + this.root = undefined; |
| 29 | + } |
| 30 | + |
| 31 | + insert(key) { |
| 32 | + // special case: first key |
| 33 | + if (this.root == null) { |
| 34 | + this.root = new Node(key); |
| 35 | + } else { |
| 36 | + this.insertNode(this.root, key); |
| 37 | + } |
| 38 | + } |
| 39 | + |
| 40 | + insertNode(node, key) { |
| 41 | + if (this.compareFn(key, node.key) === Compare.LESS_THAN) { |
| 42 | + if (node.left == null) { |
| 43 | + node.left = new Node(key); |
| 44 | + } else { |
| 45 | + this.insertNode(node.left, key); |
| 46 | + } |
| 47 | + } else if (node.right == null) { |
| 48 | + node.right = new Node(key); |
| 49 | + } else { |
| 50 | + this.insertNode(node.right, key); |
| 51 | + } |
| 52 | + } |
| 53 | + |
| 54 | + getRoot() { |
| 55 | + return this.root; |
| 56 | + } |
| 57 | + |
| 58 | + search(key) { |
| 59 | + return this.searchNode(this.root, key); |
| 60 | + } |
| 61 | + |
| 62 | + searchNode(node, key) { |
| 63 | + if (node == null) { |
| 64 | + return false; |
| 65 | + } |
| 66 | + if (this.compareFn(key, node.key) === Compare.LESS_THAN) { |
| 67 | + return this.searchNode(node.left, key); |
| 68 | + } if (this.compareFn(key, node.key) === Compare.BIGGER_THAN) { |
| 69 | + return this.searchNode(node.right, key); |
| 70 | + } |
| 71 | + return true; |
| 72 | + } |
| 73 | + |
| 74 | + inOrderTraverse(callback) { |
| 75 | + this.inOrderTraverseNode(this.root, callback); |
| 76 | + } |
| 77 | + |
| 78 | + inOrderTraverseNode(node, callback) { |
| 79 | + if (node != null) { |
| 80 | + this.inOrderTraverseNode(node.left, callback); |
| 81 | + callback(node.key); |
| 82 | + this.inOrderTraverseNode(node.right, callback); |
| 83 | + } |
| 84 | + } |
| 85 | + |
| 86 | + preOrderTraverse(callback) { |
| 87 | + this.preOrderTraverseNode(this.root, callback); |
| 88 | + } |
| 89 | + |
| 90 | + preOrderTraverseNode(node, callback) { |
| 91 | + if (node != null) { |
| 92 | + callback(node.key); |
| 93 | + this.preOrderTraverseNode(node.left, callback); |
| 94 | + this.preOrderTraverseNode(node.right, callback); |
| 95 | + } |
| 96 | + } |
| 97 | + |
| 98 | + postOrderTraverse(callback) { |
| 99 | + this.postOrderTraverseNode(this.root, callback); |
| 100 | + } |
| 101 | + |
| 102 | + postOrderTraverseNode(node, callback) { |
| 103 | + if (node != null) { |
| 104 | + this.postOrderTraverseNode(node.left, callback); |
| 105 | + this.postOrderTraverseNode(node.right, callback); |
| 106 | + callback(node.key); |
| 107 | + } |
| 108 | + } |
| 109 | + |
| 110 | + min() { |
| 111 | + return this.minNode(this.root); |
| 112 | + } |
| 113 | + |
| 114 | + minNode(node) { |
| 115 | + let current = node; |
| 116 | + while (current != null && current.left != null) { |
| 117 | + current = current.left; |
| 118 | + } |
| 119 | + return current; |
| 120 | + } |
| 121 | + |
| 122 | + max() { |
| 123 | + return this.maxNode(this.root); |
| 124 | + } |
| 125 | + |
| 126 | + maxNode(node) { |
| 127 | + let current = node; |
| 128 | + while (current != null && current.right != null) { |
| 129 | + current = current.right; |
| 130 | + } |
| 131 | + return current; |
| 132 | + } |
| 133 | + |
| 134 | + remove(key) { |
| 135 | + this.root = this.removeNode(this.root, key); |
| 136 | + } |
| 137 | + |
| 138 | + removeNode(node, key) { |
| 139 | + if (node == null) { |
| 140 | + return undefined; |
| 141 | + } |
| 142 | + if (this.compareFn(key, node.key) === Compare.LESS_THAN) { |
| 143 | + node.left = this.removeNode(node.left, key); |
| 144 | + return node; |
| 145 | + } if (this.compareFn(key, node.key) === Compare.BIGGER_THAN) { |
| 146 | + node.right = this.removeNode(node.right, key); |
| 147 | + return node; |
| 148 | + } |
| 149 | + // key is equal to node.item |
| 150 | + // handle 3 special conditions |
| 151 | + // 1 - a leaf node |
| 152 | + // 2 - a node with only 1 child |
| 153 | + // 3 - a node with 2 children |
| 154 | + // case 1 |
| 155 | + if (node.left == null && node.right == null) { |
| 156 | + node = undefined; |
| 157 | + return node; |
| 158 | + } |
| 159 | + // case 2 |
| 160 | + if (node.left == null) { |
| 161 | + node = node.right; |
| 162 | + return node; |
| 163 | + } if (node.right == null) { |
| 164 | + node = node.left; |
| 165 | + return node; |
| 166 | + } |
| 167 | + // case 3 |
| 168 | + const aux = this.minNode(node.right); |
| 169 | + node.key = aux.key; |
| 170 | + node.right = this.removeNode(node.right, aux.key); |
| 171 | + return node; |
| 172 | + } |
| 173 | +} |
| 174 | + |
| 175 | +const tree = new BinarySearchTree(); |
| 176 | +tree.insert(1); |
| 177 | +tree.insert(3); |
| 178 | +tree.insert(8); |
| 179 | +tree.insert(10); |
| 180 | +tree.insert(14); |
| 181 | +tree.insert(13); |
| 182 | +tree.insert(4); |
| 183 | +tree.insert(6); |
| 184 | +tree.insert(7); |
| 185 | +console.log(tree); |
| 186 | +tree.inOrderTraverse((v) => document.write(`${v}\n`)); |
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