问题描述
我正在尝试为双向链接列表编写一种插入方法,其中,当我将节点放入列表中时,将按字母顺序将其插入。这个想法是,我将遍历一个curnode,如果newNode在curnode之前,我将newNode放在curnode之前。到目前为止,我编写的代码可用于将1个节点插入列表,但是第二部分存在问题,需要检查顺序和放置位置。我应该如何更改程序以使其正常运行?有了代码,我现在只可以插入1个元素(头)。
void insert(String x){
node curnode = head;
node newNode = new node(x);
//list is empty so insert as normal - [works fine]
if (head == null){
head = newNode;
head.prev = null;
head.next = null;
tail = newNode;
}
//Now insert node with respect to alphabetical order - [problem area]
else {
// while the list isn't empty
while (curnode != null){
// if newNode alphabetically comes before the curnode then place before
if (curnode.data.compareto(newNode.data) > 0){
node temp = curnode.prev;
curnode.prev = newNode;
newNode.next = curnode;
newNode.prev = temp;
break;
}
}
}
}
解决方法
您的实现缺少一些东西。将其与此可行的解决方案进行比较:
void insert(String x){
node curnode = head;
node lastnode = null;
node newNode = new node(x);
//list is empty so insert as normal - [works fine]
if (head == null){
head = newNode;
head.prev = null;
head.next = null;
tail = newNode;
}
//Now insert node with respect to alphabetical order - [problem area]
else {
// while the list isn't empty
while (curnode != null){
// if newNode alphabetically comes before the curnode then place before
if (curnode.data.compareTo(newNode.data) > 0){
node temp = curnode.prev;
curnode.prev = newNode;
newNode.next = curnode;
newNode.prev = temp;
if(temp != null) {
temp.next = newNode;
} else {
// If newnode gets inserted in the head
head = newNode;
}
break;
}
lastnode = curnode;
curnode = curnode.next;
}
if (curnode == null) {
// insert to the last
lastnode.next = newNode;
newNode.prev = lastnode;
tail = newNode;
}
}
}