javascriptで2分木

Tree.js

// http://jsfiddle.net/L6bfa

var TreeNode = function (value, left, right) {
    this.value = value;
    this.left = left;
    this.right = right;
};

var Tree = function (root) {
    this.root = root;
};

Tree.prototype.leftTree = function () {
    return new Tree(this.root.left);
};

Tree.prototype.rightTree = function () {
    return new Tree(this.root.right);
};

Tree.prototype.contains = function (value) {
    if (!this.root) {
        return false;
    } else if (this.root.value == value) {
        return true;
    } else if (value > this.root.value) {
        return this.rightTree().contains(value);
    } else {
        return this.leftTree().contains(value);
    }
};

Tree.prototype.insert = function (value) {
    if (this.root.value <= value) {
        if (this.root.right) {
            this.rightTree().insert(value);
        } else {
            this.root.right = new TreeNode(value);
        }
    } else {
        if (this.root.left) {
            this.leftTree().insert(value);
        } else {
            this.root.left = new TreeNode(value);
        }
    }
    return this;
};

var n4 = new TreeNode(4, null, null),
    n7 = new TreeNode(7, null, null),
    n9 = new TreeNode(9, null, null),
    n8 = new TreeNode(8, n7, n9),
    n5 = new TreeNode(5, n4, n8),
    root = n5,
    tree = new Tree(root);

tree.insert(3).insert(10);

console.log(tree);
for (var i = 1; i <= 10; i++) {
    console.log(i, tree.contains(i));
}