Updated tasks 15-128

Author: javadev

LICENSE

@@ -1,6 +1,6 @@
 MIT License
 
-Copyright (c) 2023-2024 Valentyn Kolesnikov
+Copyright (c) 2023-2025 Valentyn Kolesnikov
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

LeetCodeNet/G0001_0100/S0015_3sum/readme.md

@@ -40,40 +40,32 @@ public class Solution {
         Array.Sort(nums);
         int len = nums.Length;
         IList<IList<int>> result = new List<IList<int>>();
-
         for (int i = 0; i < len - 2; i++) {
             int l = i + 1;
             int r = len - 1;
-
             while (r > l) {
                 int sum = nums[i] + nums[l] + nums[r];
-
                 if (sum < 0) {
                     l++;
                 } else if (sum > 0) {
                     r--;
                 } else {
                     IList<int> list = new List<int> { nums[i], nums[l], nums[r] };
                     result.Add(list);
-
                     while (l < r && nums[l + 1] == nums[l]) {
                         l++;
                     }
-
                     while (r > l && nums[r - 1] == nums[r]) {
                         r--;
                     }
-
                     l++;
                     r--;
                 }
             }
-
             while (i < len - 1 && nums[i + 1] == nums[i]) {
                 i++;
             }
         }
-
         return result;
     }
 }

LeetCodeNet/G0001_0100/S0017_letter_combinations_of_a_phone_number/readme.md

@@ -45,25 +45,25 @@ public class Solution {
             return new List<string>();
         }
         string[] letters = {"", "", "abc", "def", "ghi", "jkl", "mno", "pqrs", "tuv", "wxyz"};
-        IList<string> ans = new List<string>();
+        List<string> ans = new List<string>();
         StringBuilder sb = new StringBuilder();
         FindCombinations(0, digits, letters, sb, ans);
         return ans;
     }
 
     private void FindCombinations(
-            int start, string nums, string[] letters, StringBuilder curr, IList<string> ans) {
+            int start, string nums, string[] letters, StringBuilder curr, List<string> ans) {
         if (curr.Length == nums.Length) {
             ans.Add(curr.ToString());
             return;
         }
         for (int i = start; i < nums.Length; i++) {
-            int n = int.Parse(nums[i].ToString());
+            int n = nums[i] - '0'; // Convert char to int
             for (int j = 0; j < letters[n].Length; j++) {
                 char ch = letters[n][j];
                 curr.Append(ch);
                 FindCombinations(i + 1, nums, letters, curr, ans);
-                curr.Length--; // Equivalent to deleting the last character in StringBuilder
+                curr.Remove(curr.Length - 1, 1); // Remove last character
             }
         }
     }

LeetCodeNet/G0001_0100/S0019_remove_nth_node_from_end_of_list/readme.md

@@ -68,7 +68,6 @@ public class Solution {
         }
         RemoveNth(node.next);
         this.n--;
-
         if (this.n == 0) {
             node.next = node.next.next;
         }

LeetCodeNet/G0001_0100/S0021_merge_two_sorted_lists/readme.md

@@ -53,7 +53,6 @@ public class Solution {
     public ListNode MergeTwoLists(ListNode l1, ListNode l2) {
         ListNode list = new ListNode(-1);
         ListNode head = list;
-
         while (l1 != null || l2 != null) {
             if (l1 != null && l2 != null) {
                 if (l1.val <= l2.val) {
@@ -72,7 +71,6 @@ public class Solution {
             }
             list = list.next;
         }
-
         return head.next;
     }
 }

LeetCodeNet/G0001_0100/S0079_word_search/readme.md

@@ -68,7 +68,6 @@ public class Solution {
         char currChar = board[r][c];
         board[r][c] = '!';
         char nextChar = word[count];
-
         if (r > 0 && board[r - 1][c] == nextChar) {
             if (helper(r - 1, c, board, word, count + 1)) return true;
         }

LeetCodeNet/G0001_0100/S0084_largest_rectangle_in_histogram/readme.md

@@ -35,20 +35,16 @@ Given an array of integers `heights` representing the histogram's bar height whe
 ```csharp
 public class Solution {
     public int LargestRectangleArea(int[] heights) {
-        int maxArea = 0, i = 0;
+        int len = heights.Length;
+        int maxArea = 0;
         Stack<int> stack = new Stack<int>();
-        while (i <= heights.Length) {
-            var currHeight = i == heights.Length ? 0 : heights[i];
-            if (!stack.Any() || currHeight >= heights[stack.Peek()]) {
-                stack.Push(i);
-                i++;
-            }
-            else {
-                int index = stack.Pop();
-                int height = heights[index];
-                int width = (!stack.Any()) ? i : (i - 1) - stack.Peek();
+        for (int i = 0; i <= len; i++) {
+            while (stack.Count > 0 && (i == len || heights[stack.Peek()] >= (i < len ? heights[i] : 0))) {
+                int height = heights[stack.Pop()];
+                int width = stack.Count == 0 ? i : i - stack.Peek() - 1;
                 maxArea = Math.Max(maxArea, height * width);
             }
+            stack.Push(i);
         }
         return maxArea;
     }

LeetCodeNet/G0101_0200/S0128_longest_consecutive_sequence/readme.md

@@ -33,25 +33,29 @@ You must write an algorithm that runs in `O(n)` time.
 ```csharp
 public class Solution {
     public int LongestConsecutive(int[] nums) {
-        if (nums.Length == 0) {
-            return 0;
-        }
-        Array.Sort(nums);
-        int max = int.MinValue;
-        int thsMax = 1;
-        for (int i = 0; i < nums.Length - 1; i++) {
-            if (nums[i + 1] == nums[i] + 1) {
-                thsMax += 1;
+        Dictionary<int, int> mapToHighest = new(nums.Length);
+        int best = 0;
+        for (int i = 0; i < nums.Length; i++) {
+            int rangeLow = 0;
+            int rangeHigh = 0;
+            if (mapToHighest.ContainsKey(nums[i])) {
                 continue;
             }
-            if (nums[i + 1] == nums[i]) {
-                continue;
+            if (mapToHighest.TryGetValue(nums[i]-1, out var downCount)) {
+                rangeLow = downCount;
+            }
+            if (mapToHighest.TryGetValue(nums[i]+1, out var upCount)) {
+                rangeHigh = upCount;
+            }
+            int thisSum = rangeLow + rangeHigh + 1;
+            mapToHighest[nums[i] - rangeLow] = thisSum;
+            mapToHighest[nums[i] + rangeHigh] = thisSum;
+            if (rangeLow != 0 && rangeHigh != 0) {
+                mapToHighest[nums[i]] = 1;
             }
-            // Start of a new Sequene
-            max = Math.Max(max, thsMax);
-            thsMax = 1;
+            best = Math.Max(thisSum, best);
         }
-        return Math.Max(max, thsMax);
+        return best;
     }
 }
 ```