JS中的設計模式與數據結構之二叉排序樹

function Node(value, left, right) {
    this.value = value;
    this.left = left;
    this.right = right;
    this.show = show;
}
function show() {
    return this.value;
}

function BST() {
    this.root = null;
    this.insert = insert;
    this.preOrder = preOrder;
    this.inOrder = inOrder;
    this.postOrder = postOrder;
    this.find = find;
    this.findParent = findParent;
    this.getMin = getMin;
    this.getMax = getMax;
    this.remove = remove;  
    this.removeNode = removeNode;    
}
function insert(value) {
    let newNode = new Node(value, null, null);
    if (this.root == null) {
        this.root = newNode;
    } else {
        let currentNode = this.root;
        while (true) {
            let parentNode = currentNode;
            if (value < currentNode.value) {
                currentNode = currentNode.left;
                if (currentNode == null) {
                    parentNode.left = newNode;
                    break;
                }
            } else {
                currentNode = currentNode.right;
                if (currentNode == null) {
                    parentNode.right = newNode;
                    break;
                }
            }
        }
    }
}
function inOrder(node) {
    if (node != null) {
        inOrder(node.left);
        console.log(node.show() + ' ');
        inOrder(node.right);
    }
}
function preOrder(node) {
    if (node != null) {
        console.log(node.show() + ' ');
        preOrder(node.left);
        preOrder(node.right);
    }
}
function postOrder(node) {
    if (node != null) {
        postOrder(node.left);
        postOrder(node.right);
        console.log(node.show() + ' ');
    }
}
function getMin(node) {
    let currentNode = node;
    while (true) {
        if (currentNode.left != null) {
            currentNode = currentNode.left;
        } else {
            return currentNode.value;
        }
    }
}
function getMax(node) {
    let currentNode = node;
    while (true) {
        if (currentNode.right != null) {
            currentNode = currentNode.right;
        } else {
            return currentNode.value;
        }
    }
}
function find(value) {
    let currentNode = this.root;
    if (value == currentNode.value) {
        return currentNode;
    }
    while (true) {
        if (value < currentNode.value) {
            currentNode = currentNode.left;
            if (value == currentNode.value) {
                return currentNode;
            } else if (currentNode.left == null && currentNode.right == null) {
                break;
            }
        } else if (value > currentNode.value) {
            currentNode = currentNode.right;
            if (value == currentNode.value) {
                return currentNode;
            } else if (currentNode.left == null && currentNode.right == null) {
                break;
            }
        }
    }
    return null;
}
function findParent(value) {
    let currentNode = this.root;
    if (value == currentNode.value) {
        return null;
    }
    while (true) {
        let parentNode = currentNode;
        if (value < currentNode.value) {
            currentNode = currentNode.left;
            if (value == currentNode.value) {
                return parentNode;
            } else if (currentNode.left == null && currentNode.right == null) {
                break;
            }
        } else if (value > currentNode.value) {
            currentNode = currentNode.right;
            if (value == currentNode.value) {
                return parentNode;
            } else if (currentNode.left == null && currentNode.right == null) {
                break;
            }
        }
    }
    return null;
}

function remove( value ) {
    removeNode( this.root , value);
}
function getSmallest(node) {
    if (node.left == null) {
        return node;
    }
    else {
        return getSmallest(node.left);
    }
}
function removeNode( node , value ) {
    if( node == null ) {
        return null;
    }
    if(value == node.value) {
        if(node.left == null && node.right == null) {
            return null;
        }
        if(node.left == null) {
            return node.right;
        }
        if(node.right == null) {
            return node.left;
        }
        var tempNode = getSmallest(node.right);
        node.value = tempNode.value;
        node.right = removeNode(node.right,tempNode.value);
        return node;

    }else if(value < node.value) {
        node.left = removeNode( node.left,value);
        return node;
    }else {
        node.right = removeNode( node.right,value);
        return node;
    }
}

var bst = new BST();
bst.insert(50);
bst.insert(30);
bst.insert(60);
bst.insert(10);
bst.insert(40);
bst.insert(35);
bst.insert(32);
bst.insert(37);
bst.insert(45);
bst.inOrder(bst.root);
bst.remove(30)
console.log('-------------')
bst.inOrder(bst.root);