将元素插入链接列表中的特定索引(Javascript)
我无法弄清楚为什么我的代码不起作用,而我一直在盯着它。当我尝试调用该函数时,我会收到错误“无法读取null的属性(读取'next')”,并且由于我正在重新分配Curr并通过列表迭代,因此不会期望发生这种错误。
// insert an item at the position specified
LinkedList.prototype.insert = function(data, position) {
let newNode = new Node(data); //instantiate a new node
if (position < 0 || position > this.size) { // if the position is less than zero or greater than the size of the linked list itself
return 'Please enter a valid position.' // return error statement
} else {
if (this.head === null) { // if we do not have any nodes in the list)
this.head = newNode; // point newNode's pointer to the head
this.tail = newNode; // point the head pointer to the newNode;
} else {
let prev = null; // set up a variable to hold the prev value
let curr = this.head; // set a current variable to this.head (the start)
let currIndex = 0;
while (currIndex < position) { // while the current index we're at is less than the position, we need to keep iterating
prev = curr; // set prev variable equal to curr
curr = curr.next; // skip to next node until we find the right position
}
newNode.next = curr; // after we find the position, set the new node's next to equal the current
prev.next = newNode; // also set the previous node's next to equal the new node
}
this.size++;
}
}
console.log(myList)
myList.insert(4,1)
console.log(myList)
I cannot figure out why my code isn't working and I've been staring at it forever. When I try to call the function, I get the error "Cannot read properties of null (reading 'next')" and wouldn't have expected this to happen since I am re-assigning both curr and prev to iterate through the list.
// insert an item at the position specified
LinkedList.prototype.insert = function(data, position) {
let newNode = new Node(data); //instantiate a new node
if (position < 0 || position > this.size) { // if the position is less than zero or greater than the size of the linked list itself
return 'Please enter a valid position.' // return error statement
} else {
if (this.head === null) { // if we do not have any nodes in the list)
this.head = newNode; // point newNode's pointer to the head
this.tail = newNode; // point the head pointer to the newNode;
} else {
let prev = null; // set up a variable to hold the prev value
let curr = this.head; // set a current variable to this.head (the start)
let currIndex = 0;
while (currIndex < position) { // while the current index we're at is less than the position, we need to keep iterating
prev = curr; // set prev variable equal to curr
curr = curr.next; // skip to next node until we find the right position
}
newNode.next = curr; // after we find the position, set the new node's next to equal the current
prev.next = newNode; // also set the previous node's next to equal the new node
}
this.size++;
}
}
console.log(myList)
myList.insert(4,1)
console.log(myList)
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当我弄清楚出了什么问题时就结束了。我忘记在 while 循环中增加 currIndex ,哈哈。
Closing this out as I figured out what was wrong. I was forgetting to increment currIndex within the while loop, haha.