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1 change: 1 addition & 0 deletions
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solutions/remove-zero-sum-consecutive-nodes-from-linked-list/CMakeLists.txt
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1 @@ | ||
| add_catch(test_remove_zero_sum_consecutive_nodes_from_linked_list test.cpp) |
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solutions/remove-zero-sum-consecutive-nodes-from-linked-list/solution.hpp
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| @@ -0,0 +1,56 @@ | ||
| #pragma once | ||
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| #include <unordered_map> | ||
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| #include <list_node.h> | ||
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| namespace ps { | ||
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| // Time: O(N^2) | ||
| // Space: O(1) | ||
| class Solution { | ||
| public: | ||
| static ListNode *removeZeroSumSublists(ListNode *head) { | ||
| ListNode dummy(0, head); | ||
| for (auto *start = &dummy; start; start = start->next) { | ||
| int sum = 0; | ||
| for (auto *end = start->next; end; end = end->next) { | ||
| sum += end->val; | ||
| if (!sum) { | ||
| start->next = end->next; | ||
| } | ||
| } | ||
| } | ||
| return dummy.next; | ||
| } | ||
| }; | ||
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| } // namespace ps | ||
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| namespace ht { | ||
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| // Time: O(N) | ||
| // Space: O(N) | ||
| class Solution { | ||
| public: | ||
| static ListNode *removeZeroSumSublists(ListNode *head) { | ||
| ListNode dummy(0, head); | ||
| std::unordered_map<int, ListNode *> map; | ||
| int sum = 0; | ||
| for (auto *curr = &dummy; curr; curr = curr->next) { | ||
| sum += curr->val; | ||
| if (map.contains(sum)) { | ||
| auto *node = std::exchange(map[sum]->next, curr->next); | ||
| for (auto s = sum + node->val; s != sum; s += node->val) { | ||
| map.erase(s); | ||
| node = node->next; | ||
| } | ||
| } else { | ||
| map[sum] = curr; | ||
| } | ||
| } | ||
| return dummy.next; | ||
| } | ||
| }; | ||
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| } // namespace ht |
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solutions/remove-zero-sum-consecutive-nodes-from-linked-list/test.cpp
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,41 @@ | ||
| #include <catch.hpp> | ||
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| #include <solution.hpp> | ||
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| #include <list_node.h> | ||
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| TEST_CASE("Simple") { | ||
| struct TestCase { | ||
| List head; | ||
| List expected; | ||
| }; | ||
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| std::vector<TestCase> test_cases{ | ||
| { | ||
| .head = {1, 2, -3, 3, 1}, | ||
| .expected = {3, 1}, | ||
| }, | ||
| { | ||
| .head = {1, 2, 3, -3, 4}, | ||
| .expected = {1, 2, 4}, | ||
| }, | ||
| { | ||
| .head = {1, 2, 3, -3, -2}, | ||
| .expected = {1}, | ||
| }, | ||
| }; | ||
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| SECTION("Prefix Sum") { | ||
| for (const auto &[head, expected] : test_cases) { | ||
| const List actual = ps::Solution::removeZeroSumSublists(Copy(head)); | ||
| REQUIRE(expected == actual); | ||
| } | ||
| } | ||
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| SECTION("Hash Table") { | ||
| for (const auto &[head, expected] : test_cases) { | ||
| const List actual = ht::Solution::removeZeroSumSublists(Copy(head)); | ||
| REQUIRE(expected == actual); | ||
| } | ||
| } | ||
| } |