🟢 Port problem 83 (Remove Duplicates from Sorted List) from TypeScript to C++23

solutions/0001-0100/0083-remove-duplicates-from-sorted-list/README.md

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+# 83. Remove Duplicates from Sorted List
+
+[LeetCode problem 83](https://leetcode.com/problems/remove-duplicates-from-sorted-list/)
+
+- **Difficulty**: Easy
+- **Tags**: linked-list
+
+## Description
+
+Given the head of a sorted linked list, delete all duplicates so each
+element appears only once, and return the linked list, still sorted.

solutions/0001-0100/0083-remove-duplicates-from-sorted-list/solution.cpp

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+#include "solution.hpp"
+
+namespace leetcode::p0083 {
+
+ListNode* solve(ListNode* head) {
+    ListNode* current = head;
+
+    while (current != nullptr && current->next != nullptr) {
+        if (current->next->val == current->val) {
+            current->next = current->next->next;
+        } else {
+            current = current->next;
+        }
+    }
+
+    return head;
+}
+
+} // namespace leetcode::p0083

solutions/0001-0100/0083-remove-duplicates-from-sorted-list/solution.hpp

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+#pragma once
+
+namespace leetcode::p0083 {
+
+struct ListNode {
+    int val;
+    ListNode* next;
+
+    explicit ListNode(int value = 0, ListNode* nextNode = nullptr) : val(value), next(nextNode) {}
+};
+
+// optimized: O(n) time, O(1) extra space — walk the list once, skipping any
+// node whose value matches the current one.
+ListNode* solve(ListNode* head);
+
+} // namespace leetcode::p0083

solutions/0001-0100/0083-remove-duplicates-from-sorted-list/test.cpp

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+#include <vector>
+
+#include <catch2/catch_test_macros.hpp>
+
+#include "solution.hpp"
+
+namespace {
+
+leetcode::p0083::ListNode* fromVector(const std::vector<int>& values) {
+    leetcode::p0083::ListNode dummy;
+    leetcode::p0083::ListNode* current = &dummy;
+    for (int value : values) {
+        current->next = new leetcode::p0083::ListNode(value);
+        current = current->next;
+    }
+    return dummy.next;
+}
+
+std::vector<int> toVector(leetcode::p0083::ListNode* head) {
+    std::vector<int> result;
+    for (auto* node = head; node != nullptr; node = node->next) {
+        result.push_back(node->val);
+    }
+    return result;
+}
+
+} // namespace
+
+TEST_CASE("Problem 83", "[p0083]") {
+    CHECK(toVector(leetcode::p0083::solve(fromVector({1, 1, 2}))) == std::vector<int>{1, 2});
+    CHECK(toVector(leetcode::p0083::solve(fromVector({1, 1, 2, 3, 3}))) ==
+          std::vector<int>{1, 2, 3});
+    CHECK(toVector(leetcode::p0083::solve(fromVector({}))).empty());
+}