"TypeError: Cannot set properties of undefined (setting 'next')"
"TypeError: Cannot set properties of undefined (setting 'next')"
输入:给定两个非空链表,表示两个非负整数。数字以相反的顺序存储,并且它们的每个节点都包含一个数字。将两个数字和 return 相加作为链表。
Input & Output Illustration (open for understanding)
var addTwoNumbers = function(l1, l2) {
let carry = 0,
sum = 0;
let runningNode = new ListNode(0, null);
let headNode = runningNode;
while (l1 !== null || l2 !== null) {
sum = l1 != null ? l1.val : 0 + l2 != null ? l2.val : 0 + carry;
carry = 0;
// Error is in below line it states "TypeError: Cannot set properties of undefined (setting 'next')"
runningNode.next = ListNode(sum % 10, null)
runningNode = runningNode.next;
//How to fix it?
if (l1) {
l1.next;
}
if (l2) {
l2.next;
}
}
if (carry) {
runningNode.next = ListNode(carry);
}
return headNode;
};
几个问题:
调用构造函数时需要new
,否则this
未定义,this.next
等引用无效。您的代码中有两个地方需要进行此更正。
在对 sum
的赋值中,+
运算符优先于 ? :
运算符,但在您的情况下您希望采用另一种方式,所以您需要添加括号。
carry
永远不会设置为除 0 以外的任何值。当总和大于 9 时它应该得到 1。
最终结果总是return一个以0开头的列表,也就是head
所指的虚拟节点。这使得结果大十倍。 Return下一个节点。
更正后的代码:
var addTwoNumbers = function(l1, l2) {
let carry = 0,
sum = 0;
let runningNode = new ListNode(0, null);
let headNode = runningNode;
while (l1 !== null || l2 !== null) {
// Use parentheses to make sure the addition happens last:
sum = (l1 != null ? l1.val : 0) + (l2 != null ? l2.val : 0) + carry;
// Need to set carry
carry = Math.floor(sum / 10);
// Need "new" when calling constructor
runningNode.next = new ListNode(sum % 10, null);
runningNode = runningNode.next;
// Must assign!
if (l1) {
l1 = l1.next;
}
if (l2) {
l2 = l2.next;
}
}
if (carry) {
// Must call with "new":
runningNode.next = new ListNode(carry);
}
return headNode.next; // skip the zero node
};
输入:给定两个非空链表,表示两个非负整数。数字以相反的顺序存储,并且它们的每个节点都包含一个数字。将两个数字和 return 相加作为链表。
Input & Output Illustration (open for understanding)
var addTwoNumbers = function(l1, l2) {
let carry = 0,
sum = 0;
let runningNode = new ListNode(0, null);
let headNode = runningNode;
while (l1 !== null || l2 !== null) {
sum = l1 != null ? l1.val : 0 + l2 != null ? l2.val : 0 + carry;
carry = 0;
// Error is in below line it states "TypeError: Cannot set properties of undefined (setting 'next')"
runningNode.next = ListNode(sum % 10, null)
runningNode = runningNode.next;
//How to fix it?
if (l1) {
l1.next;
}
if (l2) {
l2.next;
}
}
if (carry) {
runningNode.next = ListNode(carry);
}
return headNode;
};
几个问题:
调用构造函数时需要
new
,否则this
未定义,this.next
等引用无效。您的代码中有两个地方需要进行此更正。在对
sum
的赋值中,+
运算符优先于? :
运算符,但在您的情况下您希望采用另一种方式,所以您需要添加括号。carry
永远不会设置为除 0 以外的任何值。当总和大于 9 时它应该得到 1。最终结果总是return一个以0开头的列表,也就是
head
所指的虚拟节点。这使得结果大十倍。 Return下一个节点。
更正后的代码:
var addTwoNumbers = function(l1, l2) {
let carry = 0,
sum = 0;
let runningNode = new ListNode(0, null);
let headNode = runningNode;
while (l1 !== null || l2 !== null) {
// Use parentheses to make sure the addition happens last:
sum = (l1 != null ? l1.val : 0) + (l2 != null ? l2.val : 0) + carry;
// Need to set carry
carry = Math.floor(sum / 10);
// Need "new" when calling constructor
runningNode.next = new ListNode(sum % 10, null);
runningNode = runningNode.next;
// Must assign!
if (l1) {
l1 = l1.next;
}
if (l2) {
l2 = l2.next;
}
}
if (carry) {
// Must call with "new":
runningNode.next = new ListNode(carry);
}
return headNode.next; // skip the zero node
};