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pony
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Add remove-linked-list-elements solution
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+199
-0
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2 files changed

+199
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lines changed

‎src/leetcode/RemoveLinkedListElements.php

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<?php
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declare(strict_types=1);
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namespace leetcode;
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use leetcode\util\ListNode;
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class RemoveLinkedListElements
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{
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public static function removeElements(?ListNode $head, int $val): ?ListNode
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{
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if (!$head) {
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return null;
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}
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$next = self::removeElements($head->next, $val);
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if ($head->val === $val) {
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return $next;
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}
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$head->next = $next;
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return $head;
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}
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public static function removeElements2(?ListNode $head, int $val): ?ListNode
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{
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if (!$head) {
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return null;
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}
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[$prev, $curr] = [null, $head];
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while ($curr) {
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if ($curr->val === $val) {
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if ($curr === $head) {
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$curr = $head = $head->next;
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} else {
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$prev->next = $curr->next;
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$curr = $curr->next;
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}
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} else {
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$prev = $curr;
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$curr = $curr->next;
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}
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}
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return $head;
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}
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public static function removeElements3(?ListNode $head, int $val): ?ListNode
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{
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if (!$head) {
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return null;
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}
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$dummy = new ListNode();
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$dummy->next = $head;
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[$prev, $curr] = [$dummy, $head];
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while ($curr) {
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if ($curr->val === $val) {
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$prev->next = $curr->next;
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} else {
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$prev = $prev->next;
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}
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$curr = $curr->next;
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}
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return $dummy->next;
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}
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public static function removeElements4(?ListNode $head, int $val): ?ListNode
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{
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if (!$head) {
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return null;
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}
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$curr = $head;
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while ($curr->next) {
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if ($curr->next->val === $val) {
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$curr->next = $curr->next->next;
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} else {
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$curr = $curr->next;
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}
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}
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return $head->val === $val ? $head->next : $head;
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}
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}

‎tests/leetcode/RemoveLinkedListElementsTest.php

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<?php
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declare(strict_types=1);
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namespace leetcode\tests;
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use PHPUnit\Framework\TestCase;
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use leetcode\RemoveLinkedListElements;
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use leetcode\util\ListNode;
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class RemoveLinkedListElementsTest extends TestCase
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{
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private ?ListNode $l1;
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private ?ListNode $l2;
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private ?ListNode $l3;
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private ?ListNode $l4;
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protected function setUp(): void
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{
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$this->l1 = new ListNode(
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1,
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new ListNode(
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2,
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new ListNode(
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6,
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new ListNode(
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3,
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new ListNode(
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4,
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new ListNode(
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5,
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new ListNode(6)
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)
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)
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)
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)
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)
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);
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$this->l2 = null;
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$this->l3 = new ListNode(
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7,
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new ListNode(
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7,
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new ListNode(
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7,
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new ListNode(
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7,
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new ListNode(7)
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)
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)
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)
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);
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$this->l4 = new ListNode(9);
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}
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public function testRemoveElements(): void
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{
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$node1 = RemoveLinkedListElements::removeElements($this->l1, 6);
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self::assertSame([1, 2, 3, 4, 5], ListNode::toArray($node1));
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$node2 = RemoveLinkedListElements::removeElements($this->l2, 1);
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self::assertSame([], ListNode::toArray($node2));
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$node3 = RemoveLinkedListElements::removeElements($this->l3, 7);
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self::assertSame([], ListNode::toArray($node3));
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$node4 = RemoveLinkedListElements::removeElements($this->l4, 9);
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self::assertSame([], ListNode::toArray($node4));
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}
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public function testRemoveElements2(): void
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{
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$node1 = RemoveLinkedListElements::removeElements2($this->l1, 6);
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self::assertSame([1, 2, 3, 4, 5], ListNode::toArray($node1));
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$node2 = RemoveLinkedListElements::removeElements2($this->l2, 1);
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self::assertSame([], ListNode::toArray($node2));
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$node3 = RemoveLinkedListElements::removeElements2($this->l3, 7);
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self::assertSame([], ListNode::toArray($node3));
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$node4 = RemoveLinkedListElements::removeElements2($this->l4, 9);
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self::assertSame([], ListNode::toArray($node4));
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}
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public function testRemoveElements3(): void
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{
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$node1 = RemoveLinkedListElements::removeElements3($this->l1, 6);
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self::assertSame([1, 2, 3, 4, 5], ListNode::toArray($node1));
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$node2 = RemoveLinkedListElements::removeElements3($this->l2, 1);
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self::assertSame([], ListNode::toArray($node2));
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$node3 = RemoveLinkedListElements::removeElements3($this->l3, 7);
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self::assertSame([], ListNode::toArray($node3));
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$node4 = RemoveLinkedListElements::removeElements3($this->l4, 9);
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self::assertSame([], ListNode::toArray($node4));
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}
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public function testRemoveElements4(): void
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{
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$node1 = RemoveLinkedListElements::removeElements4($this->l1, 6);
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self::assertSame([1, 2, 3, 4, 5], ListNode::toArray($node1));
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$node2 = RemoveLinkedListElements::removeElements4($this->l2, 1);
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self::assertSame([], ListNode::toArray($node2));
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$node3 = RemoveLinkedListElements::removeElements4($this->l3, 7);
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self::assertSame([], ListNode::toArray($node3));
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$node4 = RemoveLinkedListElements::removeElements4($this->l4, 9);
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self::assertSame([], ListNode::toArray($node4));
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}
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}

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