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Commit b77ac6b

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feat(LC): add 876, successful answer, optimized, notes
1 parent 9a1145b commit b77ac6b

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3 files changed

+118
-5
lines changed

3 files changed

+118
-5
lines changed

‎LeetCode/###_leetcode.template.js

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/**
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* CODE
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* TIME:
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* MEMORY:
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*/
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/**
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* READ 0
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* EXPLAIN 0
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* APPROACH 0
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* CODE [FAIl] 0
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* CODE [FAIL] 0
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* TEST 0
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* OPTIMIZE 0
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*/

‎LeetCode/Completed/206_ReverseLinkedList/206_leetcode.js

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@@ -49,10 +49,10 @@ var reverseList = function (currNode, prevNode) {};
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*/
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/**
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* READ 0
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* EXPLAIN 0
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* APPROACH 0
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* CODE [FAIl] 0
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* READ 01:29
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* EXPLAIN 11:54 13:23
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* APPROACH 09:01 22:25
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* CODE [FAIl] 10:14 32:39
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* TEST 0
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* OPTIMIZE 0
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*/
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/**
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* @see {@link https://leetcode.com/problems/middle-of-the-linked-list/?envType=study-plan&id=level-1 876. Middle of the Linked List}
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*/
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/**
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* EXPLAIN
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*
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* given LL return
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* middle node if LL has ODD length
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* 2nd middle if LL has even length
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*
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* guaranteed to always have at least 1 node, at most 100
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* vals are between 1 and 100
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*/
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/**
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* APPROACH
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*
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* returning a NODE
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* need a pointer to know what node to return, this is mid node
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* need a pointer to advance the LL node searcher
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* need a flag to know WHEN to advance mid node, defaults to true, then flips
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*
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*
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* START LOOP
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* IF no node.next
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* return mid node
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* ELSE (node.next DOES exists)
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* advance LL node searcher to next node
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*
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* IF flag to advance mid node is true
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* advance mid node pointer
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* set flag to false
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* ELSE
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* set flag to true to trigger mid advancement NEXT loop
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* if reaches this point
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* do nothing else
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* END LOOP
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*
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* curr endPointer is null, reached end of LL
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* return current mid node
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*/
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/**
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* CODE
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* TIME: 75ms - 47%
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* MEMORY: 42.3MB - 25%
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*/
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/**
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* Definition for singly-linked list.
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* function ListNode(val, next) {
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* this.val = (val===undefined ? 0 : val)
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* this.next = (next===undefined ? null : next)
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* }
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*/
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/**
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* @param {ListNode} head
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* @return {ListNode}
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*/
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var middleNode = function (head) {
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let endNode = head;
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let midNode = head;
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let advanceMidNode = true;
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while (endNode) {
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if (!endNode.next) {
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return midNode;
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}
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endNode = endNode.next;
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if (advanceMidNode) {
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midNode = midNode.next;
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}
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advanceMidNode = !advanceMidNode;
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}
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return midNode;
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};
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/**
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* OPTIMIZED
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* TIME: 66ms - 69%
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* MEMORY: 42.1MB - 49%
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* Uses a fast pointer that advances two at a time
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* and a slow pointer that advances one at a time
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*/
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var middleNode = function (head) {
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let fast = head.next;
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while (fast) {
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head = head.next;
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fast = fast.next?.next;
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}
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return head;
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};
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/**
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* COMPLEXITY
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* TIME O(n), where n is the length of the LL
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* SPACE O(1), only ever storing one node per variable at a time, not a growing value set
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*/
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/**
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* READ 00:47
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* EXPLAIN 01:31 02:18
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* APPROACH 12:48 15:07
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* CODE [PASS] 12:27 27:36
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* TEST 06:01 33:37
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* OPTIMIZE 24:37 58:38
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*/

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