LeetCode 234. Palindrome Linked List, a TLE weird case
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Here is my AC submission. And I found a wierd circumstances when I remove this line dumyHead->next = NULL; my submission will yield a TLE.
I know if I don't set it to NULL it will cause a loop reference, but I use len as a counter to iterate over the list, so when len <= 0 the loop will stop. I run in my local env it stopped, but in leet code it TLE.
I use "Run Code" Function in LeetCode, so there is only one case. My test case is [1,2,1]
So How dose this happen? Is it released to compiler? My local env is macOS, use g++ (detail in the end of this question).
My full code
/**
* Definition for singly-linked list.
* struct ListNode {
* int val;
* ListNode *next;
* ListNode(int x) : val(x), next(NULL) {}
* };
*/
class Solution {
public:
bool isPalindrome(ListNode* head) {
if(head == NULL) {
return true;
}
int len = 1;
ListNode* check = head->next;
while(check != NULL) {
check = check->next;
len++;
}
check = head->next;
ListNode* prev = head;
for(int i = 0; i < len / 2; i++) {
prev = check;
check = check->next;
}
// reverse
ListNode* dumyHead = prev;
ListNode* tmp = NULL;
while(check != NULL) {
tmp = check->next;
check->next = prev;
prev = check;
check = tmp;
}
// comment this line will cause TLE
dumyHead->next = NULL;
len /= 2;
while(len > 0) {
if(prev->val != head->val) {
return false;
}
prev = prev->next;
head = head->next;
len--;
}
return true;
}
};
My local env is macOS 10.14.1
g++ version:
Configured with: --prefix=/Library/Developer/CommandLineTools/usr --with-gxx-include-dir=/usr/include/c++/4.2.1
Apple LLVM version 10.0.0 (clang-1000.10.44.4)
Target: x86_64-apple-darwin18.2.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin
c++ algorithm time-limit-exceeded
edited 6 mins ago
Sᴀᴍ Onᴇᴌᴀ
8,11961751
asked 19 mins ago
Li Jinyao
12
New contributor
Li Jinyao is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |
up vote
0
down vote
favorite
Here is my AC submission. And I found a wierd circumstances when I remove this line dumyHead->next = NULL; my submission will yield a TLE.
I know if I don't set it to NULL it will cause a loop reference, but I use len as a counter to iterate over the list, so when len <= 0 the loop will stop. I run in my local env it stopped, but in leet code it TLE.
I use "Run Code" Function in LeetCode, so there is only one case. My test case is [1,2,1]
So How dose this happen? Is it released to compiler? My local env is macOS, use g++ (detail in the end of this question).
My full code
/**
* Definition for singly-linked list.
* struct ListNode {
* int val;
* ListNode *next;
* ListNode(int x) : val(x), next(NULL) {}
* };
*/
class Solution {
public:
bool isPalindrome(ListNode* head) {
if(head == NULL) {
return true;
}
int len = 1;
ListNode* check = head->next;
while(check != NULL) {
check = check->next;
len++;
}
check = head->next;
ListNode* prev = head;
for(int i = 0; i < len / 2; i++) {
prev = check;
check = check->next;
}
// reverse
ListNode* dumyHead = prev;
ListNode* tmp = NULL;
while(check != NULL) {
tmp = check->next;
check->next = prev;
prev = check;
check = tmp;
}
// comment this line will cause TLE
dumyHead->next = NULL;
len /= 2;
while(len > 0) {
if(prev->val != head->val) {
return false;
}
prev = prev->next;
head = head->next;
len--;
}
return true;
}
};
My local env is macOS 10.14.1
g++ version:
Configured with: --prefix=/Library/Developer/CommandLineTools/usr --with-gxx-include-dir=/usr/include/c++/4.2.1
Apple LLVM version 10.0.0 (clang-1000.10.44.4)
Target: x86_64-apple-darwin18.2.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin
c++ algorithm time-limit-exceeded
edited 6 mins ago
Sᴀᴍ Onᴇᴌᴀ
8,11961751
asked 19 mins ago
Li Jinyao
12
New contributor
Li Jinyao is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |
up vote
0
down vote
favorite
up vote
0
down vote
favorite
Here is my AC submission. And I found a wierd circumstances when I remove this line dumyHead->next = NULL; my submission will yield a TLE.
I know if I don't set it to NULL it will cause a loop reference, but I use len as a counter to iterate over the list, so when len <= 0 the loop will stop. I run in my local env it stopped, but in leet code it TLE.
I use "Run Code" Function in LeetCode, so there is only one case. My test case is [1,2,1]
So How dose this happen? Is it released to compiler? My local env is macOS, use g++ (detail in the end of this question).
My full code
/**
* Definition for singly-linked list.
* struct ListNode {
* int val;
* ListNode *next;
* ListNode(int x) : val(x), next(NULL) {}
* };
*/
class Solution {
public:
bool isPalindrome(ListNode* head) {
if(head == NULL) {
return true;
}
int len = 1;
ListNode* check = head->next;
while(check != NULL) {
check = check->next;
len++;
}
check = head->next;
ListNode* prev = head;
for(int i = 0; i < len / 2; i++) {
prev = check;
check = check->next;
}
// reverse
ListNode* dumyHead = prev;
ListNode* tmp = NULL;
while(check != NULL) {
tmp = check->next;
check->next = prev;
prev = check;
check = tmp;
}
// comment this line will cause TLE
dumyHead->next = NULL;
len /= 2;
while(len > 0) {
if(prev->val != head->val) {
return false;
}
prev = prev->next;
head = head->next;
len--;
}
return true;
}
};
My local env is macOS 10.14.1
g++ version:
Configured with: --prefix=/Library/Developer/CommandLineTools/usr --with-gxx-include-dir=/usr/include/c++/4.2.1
Apple LLVM version 10.0.0 (clang-1000.10.44.4)
Target: x86_64-apple-darwin18.2.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin
c++ algorithm time-limit-exceeded
edited 6 mins ago
Sᴀᴍ Onᴇᴌᴀ
8,11961751
asked 19 mins ago
Li Jinyao
12
New contributor
Li Jinyao is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
Here is my AC submission. And I found a wierd circumstances when I remove this line dumyHead->next = NULL; my submission will yield a TLE.
I know if I don't set it to NULL it will cause a loop reference, but I use len as a counter to iterate over the list, so when len <= 0 the loop will stop. I run in my local env it stopped, but in leet code it TLE.
I use "Run Code" Function in LeetCode, so there is only one case. My test case is [1,2,1]
So How dose this happen? Is it released to compiler? My local env is macOS, use g++ (detail in the end of this question).
My full code
/**
* Definition for singly-linked list.
* struct ListNode {
* int val;
* ListNode *next;
* ListNode(int x) : val(x), next(NULL) {}
* };
*/
class Solution {
public:
bool isPalindrome(ListNode* head) {
if(head == NULL) {
return true;
}
int len = 1;
ListNode* check = head->next;
while(check != NULL) {
check = check->next;
len++;
}
check = head->next;
ListNode* prev = head;
for(int i = 0; i < len / 2; i++) {
prev = check;
check = check->next;
}
// reverse
ListNode* dumyHead = prev;
ListNode* tmp = NULL;
while(check != NULL) {
tmp = check->next;
check->next = prev;
prev = check;
check = tmp;
}
// comment this line will cause TLE
dumyHead->next = NULL;
len /= 2;
while(len > 0) {
if(prev->val != head->val) {
return false;
}
prev = prev->next;
head = head->next;
len--;
}
return true;
}
};
My local env is macOS 10.14.1
g++ version:
Configured with: --prefix=/Library/Developer/CommandLineTools/usr --with-gxx-include-dir=/usr/include/c++/4.2.1
Apple LLVM version 10.0.0 (clang-1000.10.44.4)
Target: x86_64-apple-darwin18.2.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin
c++ algorithm time-limit-exceeded
c++ algorithm time-limit-exceeded
edited 6 mins ago
Sᴀᴍ Onᴇᴌᴀ
8,11961751
asked 19 mins ago
Li Jinyao
12
New contributor
Li Jinyao is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
edited 6 mins ago
Sᴀᴍ Onᴇᴌᴀ
8,11961751
asked 19 mins ago
Li Jinyao
12
New contributor
Li Jinyao is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
edited 6 mins ago
Sᴀᴍ Onᴇᴌᴀ
8,11961751
edited 6 mins ago
Sᴀᴍ Onᴇᴌᴀ
8,11961751
edited 6 mins ago
Sᴀᴍ Onᴇᴌᴀ
8,11961751
8,11961751
asked 19 mins ago
Li Jinyao
12
New contributor
Li Jinyao is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 19 mins ago
Li Jinyao
12
asked 19 mins ago
Li Jinyao
12
12
New contributor
Li Jinyao is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
Li Jinyao is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
Li Jinyao is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |
add a comment |
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