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‎README.md

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Original file line numberDiff line numberDiff line change
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| <!-- --> | <!-- --> | <!-- --> | <!-- --> | <!-- --> | <!-- -->
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|-|-|-|-|-|-
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| 0136 |[Single Number](src/main/c/g0101_0200/s0136_single_number)| Easy | Top_100_Liked_Questions, Top_Interview_Questions, Array, Bit_Manipulation, Big_O_Time_O(N)_Space_O(1) | 0 | 100.00
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| 0015 |[3Sum](src/main/c/g0001_0100/s0015_3sum)| Medium | Top_100_Liked_Questions, Top_Interview_Questions, Array, Sorting, Two_Pointers, Big_O_Time_O(n\*log(n))_Space_O(n^2) | 47 | 87.75
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#### Day 2 Array
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| <!-- --> | <!-- --> | <!-- --> | <!-- --> | <!-- --> | <!-- -->
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|-|-|-|-|-|-
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| 0002 |[Add Two Numbers](src/main/c/g0001_0100/s0002_add_two_numbers)| Medium | Top_100_Liked_Questions, Top_Interview_Questions, Math, Linked_List, Recursion, Big_O_Time_O(max(N,M))_Space_O(max(N,M)), AI_can_be_used_to_solve_the_task | 12 | 70.50
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| 0142 |[Linked List Cycle II](src/main/c/g0101_0200/s0142_linked_list_cycle_ii)| Medium | Top_100_Liked_Questions, Hash_Table, Two_Pointers, Linked_List, Big_O_Time_O(N)_Space_O(1) | 4 | 81.55
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#### Day 11 Linked List
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@@ -211,6 +213,7 @@
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212214
| <!-- --> | <!-- --> | <!-- --> | <!-- --> | <!-- --> | <!-- -->
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|-|-|-|-|-|-
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| 0136 |[Single Number](src/main/c/g0101_0200/s0136_single_number)| Easy | Top_100_Liked_Questions, Top_Interview_Questions, Array, Bit_Manipulation, Big_O_Time_O(N)_Space_O(1) | 0 | 100.00
214217

215218
### Algorithm II
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@@ -302,6 +305,7 @@
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| <!-- --> | <!-- --> | <!-- --> | <!-- --> | <!-- --> | <!-- -->
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|-|-|-|-|-|-
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| 0139 |[Word Break](src/main/c/g0101_0200/s0139_word_break)| Medium | Top_100_Liked_Questions, Top_Interview_Questions, String, Hash_Table, Dynamic_Programming, Trie, Memoization, Big_O_Time_O(M+max\*N)_Space_O(M+N+max) | 0 | 100.00
305309

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#### Day 16 Dynamic Programming
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@@ -542,6 +546,7 @@
542546

543547
| <!-- --> | <!-- --> | <!-- --> | <!-- --> | <!-- --> | <!-- -->
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|-|-|-|-|-|-
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| 0121 |[Best Time to Buy and Sell Stock](src/main/c/g0101_0200/s0121_best_time_to_buy_and_sell_stock)| Easy | Top_100_Liked_Questions, Top_Interview_Questions, Array, Dynamic_Programming, Big_O_Time_O(N)_Space_O(1) | 0 | 100.00
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546551
#### Day 8
547552

@@ -552,6 +557,7 @@
552557

553558
| <!-- --> | <!-- --> | <!-- --> | <!-- --> | <!-- --> | <!-- -->
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|-|-|-|-|-|-
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| 0139 |[Word Break](src/main/c/g0101_0200/s0139_word_break)| Medium | Top_100_Liked_Questions, Top_Interview_Questions, String, Hash_Table, Dynamic_Programming, Trie, Memoization, Big_O_Time_O(M+max\*N)_Space_O(M+N+max) | 0 | 100.00
555561
| 0042 |[Trapping Rain Water](src/main/c/g0001_0100/s0042_trapping_rain_water)| Hard | Top_100_Liked_Questions, Top_Interview_Questions, Array, Dynamic_Programming, Two_Pointers, Stack, Monotonic_Stack, Big_O_Time_O(n)_Space_O(1) | 0 | 100.00
556562

557563
#### Day 10
@@ -755,6 +761,7 @@
755761

756762
| <!-- --> | <!-- --> | <!-- --> | <!-- --> | <!-- --> | <!-- -->
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|-|-|-|-|-|-
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| 0138 |[Copy List with Random Pointer](src/main/c/g0101_0200/s0138_copy_list_with_random_pointer)| Medium | Top_100_Liked_Questions, Top_Interview_Questions, Hash_Table, Linked_List, Big_O_Time_O(N)_Space_O(N) | 4 | 91.18
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759766
#### Day 15
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933940

934941
| <!-- --> | <!-- --> | <!-- --> | <!-- --> | <!-- --> | <!-- -->
935942
|-|-|-|-|-|-
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| 0142 |[Linked List Cycle II](src/main/c/g0101_0200/s0142_linked_list_cycle_ii)| Medium | Top_100_Liked_Questions, Hash_Table, Two_Pointers, Linked_List, Big_O_Time_O(N)_Space_O(1) | 4 | 81.55
936944

937945
#### Day 5 Greedy
938946

939947
| <!-- --> | <!-- --> | <!-- --> | <!-- --> | <!-- --> | <!-- -->
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| 0121 |[Best Time to Buy and Sell Stock](src/main/c/g0101_0200/s0121_best_time_to_buy_and_sell_stock)| Easy | Top_100_Liked_Questions, Top_Interview_Questions, Array, Dynamic_Programming, Big_O_Time_O(N)_Space_O(1) | 0 | 100.00
941950

942951
#### Day 6 Tree
943952

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11111120

11121121
| <!-- --> | <!-- --> | <!-- --> | <!-- --> | <!-- --> | <!-- -->
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|-|-|-|-|-|-
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| 0136 |[Single Number](src/main/c/g0101_0200/s0136_single_number)| Easy | Top_100_Liked_Questions, Top_Interview_Questions, Array, Bit_Manipulation, Big_O_Time_O(N)_Space_O(1) | 0 | 100.00
11141124
| 0007 |[Reverse Integer](src/main/c/g0001_0100/s0007_reverse_integer)| Medium | Top_Interview_Questions, Math | 0 | 100.00
11151125
| 0009 |[Palindrome Number](src/main/c/g0001_0100/s0009_palindrome_number)| Easy | Math | 0 | 100.00
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11341144
| <!-- --> | <!-- --> | <!-- --> | <!-- --> | <!-- --> | <!-- -->
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|-|-|-|-|-|-
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| 0121 |[Best Time to Buy and Sell Stock](src/main/c/g0101_0200/s0121_best_time_to_buy_and_sell_stock)| Easy | Top_100_Liked_Questions, Top_Interview_Questions, Array, Dynamic_Programming, Big_O_Time_O(N)_Space_O(1) | 0 | 100.00
11361147
| 0001 |[Two Sum](src/main/c/g0001_0100/s0001_two_sum)| Easy | Top_100_Liked_Questions, Top_Interview_Questions, Array, Hash_Table, Big_O_Time_O(n)_Space_O(n), AI_can_be_used_to_solve_the_task | 2 | 99.56
11371148
| 0055 |[Jump Game](src/main/c/g0001_0100/s0055_jump_game)| Medium | Top_100_Liked_Questions, Top_Interview_Questions, Array, Dynamic_Programming, Greedy, Big_O_Time_O(n)_Space_O(1) | 0 | 100.00
11381149
| 0075 |[Sort Colors](src/main/c/g0001_0100/s0075_sort_colors)| Medium | Top_100_Liked_Questions, Top_Interview_Questions, Array, Sorting, Two_Pointers, Big_O_Time_O(n)_Space_O(1) | 0 | 100.00
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|-|-|-|-|-|-
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| 0114 |[Flatten Binary Tree to Linked List](src/main/c/g0101_0200/s0114_flatten_binary_tree_to_linked_list)| Medium | Top_100_Liked_Questions, Depth_First_Search, Tree, Binary_Tree, Stack, Linked_List, Big_O_Time_O(N)_Space_O(N) | 0 | 100.00
11731184
| 0024 |[Swap Nodes in Pairs](src/main/c/g0001_0100/s0024_swap_nodes_in_pairs)| Medium | Top_100_Liked_Questions, Linked_List, Recursion, Big_O_Time_O(n)_Space_O(1) | 0 | 100.00
1185+
| 0142 |[Linked List Cycle II](src/main/c/g0101_0200/s0142_linked_list_cycle_ii)| Medium | Top_100_Liked_Questions, Hash_Table, Two_Pointers, Linked_List, Big_O_Time_O(N)_Space_O(1) | 4 | 81.55
1186+
| 0141 |[Linked List Cycle](src/main/c/g0101_0200/s0141_linked_list_cycle)| Easy | Top_100_Liked_Questions, Top_Interview_Questions, Hash_Table, Two_Pointers, Linked_List, Big_O_Time_O(N)_Space_O(1) | 6 | 92.85
11741187
| 0021 |[Merge Two Sorted Lists](src/main/c/g0001_0100/s0021_merge_two_sorted_lists)| Easy | Top_100_Liked_Questions, Top_Interview_Questions, Linked_List, Recursion, Big_O_Time_O(m+n)_Space_O(m+n) | 0 | 100.00
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| 0138 |[Copy List with Random Pointer](src/main/c/g0101_0200/s0138_copy_list_with_random_pointer)| Medium | Top_100_Liked_Questions, Top_Interview_Questions, Hash_Table, Linked_List, Big_O_Time_O(N)_Space_O(N) | 4 | 91.18
11751189
| 0025 |[Reverse Nodes in k-Group](src/main/c/g0001_0100/s0025_reverse_nodes_in_k_group)| Hard | Top_100_Liked_Questions, Linked_List, Recursion, Big_O_Time_O(n)_Space_O(k) | 0 | 100.00
1190+
| 0146 |[LRU Cache](src/main/c/g0101_0200/s0146_lru_cache)| Medium | Top_100_Liked_Questions, Top_Interview_Questions, Hash_Table, Design, Linked_List, Doubly_Linked_List, Big_O_Time_O(1)_Space_O(capacity) | 37 | 91.67
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11771192
#### Udemy Tree Stack Queue
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| 0094 |[Binary Tree Inorder Traversal](src/main/c/g0001_0100/s0094_binary_tree_inorder_traversal)| Easy | Top_100_Liked_Questions, Top_Interview_Questions, Depth_First_Search, Tree, Binary_Tree, Stack, Big_O_Time_O(n)_Space_O(n) | 0 | 100.00
11821197
| 0102 |[Binary Tree Level Order Traversal](src/main/c/g0101_0200/s0102_binary_tree_level_order_traversal)| Medium | Top_100_Liked_Questions, Top_Interview_Questions, Breadth_First_Search, Tree, Binary_Tree, Big_O_Time_O(N)_Space_O(N) | 0 | 100.00
11831198
| 0104 |[Maximum Depth of Binary Tree](src/main/c/g0101_0200/s0104_maximum_depth_of_binary_tree)| Easy | Top_100_Liked_Questions, Top_Interview_Questions, Depth_First_Search, Breadth_First_Search, Tree, Binary_Tree, Big_O_Time_O(N)_Space_O(H) | 0 | 100.00
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| 0124 |[Binary Tree Maximum Path Sum](src/main/c/g0101_0200/s0124_binary_tree_maximum_path_sum)| Hard | Top_100_Liked_Questions, Top_Interview_Questions, Dynamic_Programming, Depth_First_Search, Tree, Binary_Tree, Big_O_Time_O(N)_Space_O(N) | 0 | 100.00
11841200
| 0098 |[Validate Binary Search Tree](src/main/c/g0001_0100/s0098_validate_binary_search_tree)| Medium | Top_100_Liked_Questions, Top_Interview_Questions, Depth_First_Search, Tree, Binary_Tree, Binary_Search_Tree, Big_O_Time_O(N)_Space_O(log(N)) | 0 | 100.00
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11861202
#### Udemy Trie and Heap
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| <!-- --> | <!-- --> | <!-- --> | <!-- --> | <!-- --> | <!-- -->
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| 0139 |[Word Break](src/main/c/g0101_0200/s0139_word_break)| Medium | Top_100_Liked_Questions, Top_Interview_Questions, String, Hash_Table, Dynamic_Programming, Trie, Memoization, Big_O_Time_O(M+max\*N)_Space_O(M+N+max) | 0 | 100.00
12001217
| 0070 |[Climbing Stairs](src/main/c/g0001_0100/s0070_climbing_stairs)| Easy | Top_100_Liked_Questions, Top_Interview_Questions, Dynamic_Programming, Math, Memoization, Big_O_Time_O(n)_Space_O(n) | 1 | 100.00
12011218
| 0064 |[Minimum Path Sum](src/main/c/g0001_0100/s0064_minimum_path_sum)| Medium | Top_100_Liked_Questions, Array, Dynamic_Programming, Matrix, Big_O_Time_O(m\*n)_Space_O(m\*n) | 0 | 100.00
12021219
| 0072 |[Edit Distance](src/main/c/g0001_0100/s0072_edit_distance)| Medium | Top_100_Liked_Questions, String, Dynamic_Programming, Big_O_Time_O(n^2)_Space_O(n2) | 0 | 100.00
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| <!-- --> | <!-- --> | <!-- --> | <!-- --> | <!-- --> | <!-- -->
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|-|-|-|-|-|-
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| 0121 |[Best Time to Buy and Sell Stock](src/main/c/g0101_0200/s0121_best_time_to_buy_and_sell_stock)| Easy | Top_100_Liked_Questions, Top_Interview_Questions, Array, Dynamic_Programming, Big_O_Time_O(N)_Space_O(1) | 0 | 100.00
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#### Day 4 Array
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| <!-- --> | <!-- --> | <!-- --> | <!-- --> | <!-- --> | <!-- -->
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| 0141 |[Linked List Cycle](src/main/c/g0101_0200/s0141_linked_list_cycle)| Easy | Top_100_Liked_Questions, Top_Interview_Questions, Hash_Table, Two_Pointers, Linked_List, Big_O_Time_O(N)_Space_O(1) | 6 | 92.85
12641283
| 0021 |[Merge Two Sorted Lists](src/main/c/g0001_0100/s0021_merge_two_sorted_lists)| Easy | Top_100_Liked_Questions, Top_Interview_Questions, Linked_List, Recursion, Big_O_Time_O(m+n)_Space_O(m+n) | 0 | 100.00
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#### Day 8 Linked List
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| # | Title | Difficulty | Tag | Time, ms | Time, %
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|------|----------------|-------------|-------------|----------|--------
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| 0146 |[LRU Cache](src/main/c/g0101_0200/s0146_lru_cache)| Medium | Top_100_Liked_Questions, Top_Interview_Questions, Hash_Table, Design, Linked_List, Doubly_Linked_List, Udemy_Linked_List, Big_O_Time_O(1)_Space_O(capacity) | 37 | 91.67
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| 0142 |[Linked List Cycle II](src/main/c/g0101_0200/s0142_linked_list_cycle_ii)| Medium | Top_100_Liked_Questions, Hash_Table, Two_Pointers, Linked_List, Data_Structure_II_Day_10_Linked_List, Level_1_Day_4_Linked_List, Udemy_Linked_List, Big_O_Time_O(N)_Space_O(1) | 4 | 81.55
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| 0141 |[Linked List Cycle](src/main/c/g0101_0200/s0141_linked_list_cycle)| Easy | Top_100_Liked_Questions, Top_Interview_Questions, Hash_Table, Two_Pointers, Linked_List, Data_Structure_I_Day_7_Linked_List, Udemy_Linked_List, Big_O_Time_O(N)_Space_O(1) | 6 | 92.85
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| 0139 |[Word Break](src/main/c/g0101_0200/s0139_word_break)| Medium | Top_100_Liked_Questions, Top_Interview_Questions, String, Hash_Table, Dynamic_Programming, Trie, Memoization, Algorithm_II_Day_15_Dynamic_Programming, Dynamic_Programming_I_Day_9, Udemy_Dynamic_Programming, Big_O_Time_O(M+max\*N)_Space_O(M+N+max) | 0 | 100.00
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| 0138 |[Copy List with Random Pointer](src/main/c/g0101_0200/s0138_copy_list_with_random_pointer)| Medium | Top_100_Liked_Questions, Top_Interview_Questions, Hash_Table, Linked_List, Programming_Skills_II_Day_14, Udemy_Linked_List, Big_O_Time_O(N)_Space_O(N) | 4 | 91.18
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| 0136 |[Single Number](src/main/c/g0101_0200/s0136_single_number)| Easy | Top_100_Liked_Questions, Top_Interview_Questions, Array, Bit_Manipulation, Data_Structure_II_Day_1_Array, Algorithm_I_Day_14_Bit_Manipulation, Udemy_Integers, Big_O_Time_O(N)_Space_O(1) | 0 | 100.00
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| 0131 |[Palindrome Partitioning](src/main/c/g0101_0200/s0131_palindrome_partitioning)| Medium | Top_100_Liked_Questions, Top_Interview_Questions, Array, Hash_Table, Union_Find, Big_O_Time_O(N_log_N)_Space_O(1) | 19 | 89.29
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| 0128 |[Longest Consecutive Sequence](src/main/c/g0101_0200/s0128_longest_consecutive_sequence)| Medium | Top_100_Liked_Questions, Top_Interview_Questions, Array, Hash_Table, Union_Find, Big_O_Time_O(N_log_N)_Space_O(1) | 19 | 89.29
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| 0124 |[Binary Tree Maximum Path Sum](src/main/c/g0101_0200/s0124_binary_tree_maximum_path_sum)| Hard | Top_100_Liked_Questions, Top_Interview_Questions, Dynamic_Programming, Depth_First_Search, Tree, Binary_Tree, Udemy_Tree_Stack_Queue, Big_O_Time_O(N)_Space_O(N) | 0 | 100.00
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| 0121 |[Best Time to Buy and Sell Stock](src/main/c/g0101_0200/s0121_best_time_to_buy_and_sell_stock)| Easy | Top_100_Liked_Questions, Top_Interview_Questions, Array, Dynamic_Programming, Data_Structure_I_Day_3_Array, Dynamic_Programming_I_Day_7, Level_1_Day_5_Greedy, Udemy_Arrays, Big_O_Time_O(N)_Space_O(1) | 0 | 100.00
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| 0114 |[Flatten Binary Tree to Linked List](src/main/c/g0101_0200/s0114_flatten_binary_tree_to_linked_list)| Medium | Top_100_Liked_Questions, Depth_First_Search, Tree, Binary_Tree, Stack, Linked_List, Udemy_Linked_List, Big_O_Time_O(N)_Space_O(N) | 0 | 100.00
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| 0105 |[Construct Binary Tree from Preorder and Inorder Traversal](src/main/c/g0101_0200/s0105_construct_binary_tree_from_preorder_and_inorder_traversal)| Medium | Top_100_Liked_Questions, Top_Interview_Questions, Array, Hash_Table, Tree, Binary_Tree, Divide_and_Conquer, Data_Structure_II_Day_15_Tree, Big_O_Time_O(N)_Space_O(N) | 3 | 95.24
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| 0104 |[Maximum Depth of Binary Tree](src/main/c/g0101_0200/s0104_maximum_depth_of_binary_tree)| Easy | Top_100_Liked_Questions, Top_Interview_Questions, Depth_First_Search, Breadth_First_Search, Tree, Binary_Tree, Data_Structure_I_Day_11_Tree, Programming_Skills_I_Day_10_Linked_List_and_Tree, Udemy_Tree_Stack_Queue, Big_O_Time_O(N)_Space_O(H) | 0 | 100.00

‎src/main/c/g0101_0200/s0121_best_time_to_buy_and_sell_stock/readme.md

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[![](https://img.shields.io/github/stars/LeetCode-in-C/LeetCode-in-C?label=Stars&style=flat-square)](https://github.com/LeetCode-in-C/LeetCode-in-C)
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[![](https://img.shields.io/github/forks/LeetCode-in-C/LeetCode-in-C?label=Fork%20me%20on%20GitHub%20&style=flat-square)](https://github.com/LeetCode-in-C/LeetCode-in-C/fork)
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## 121\. Best Time to Buy and Sell Stock
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Easy
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You are given an array `prices` where `prices[i]` is the price of a given stock on the <code>i<sup>th</sup></code> day.
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You want to maximize your profit by choosing a **single day** to buy one stock and choosing a **different day in the future** to sell that stock.
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Return _the maximum profit you can achieve from this transaction_. If you cannot achieve any profit, return `0`.
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**Example 1:**
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**Input:** prices = [7,1,5,3,6,4]
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**Output:** 5
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**Explanation:** Buy on day 2 (price = 1) and sell on day 5 (price = 6), profit = 6-1 = 5.
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Note that buying on day 2 and selling on day 1 is not allowed because you must buy before you sell.
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**Example 2:**
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**Input:** prices = [7,6,4,3,1]
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**Output:** 0
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**Explanation:** In this case, no transactions are done and the max profit = 0.
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**Constraints:**
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* <code>1 <= prices.length <= 10<sup>5</sup></code>
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* <code>0 <= prices[i] <= 10<sup>4</sup></code>
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## Solution
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```c
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#include <stdio.h>
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int maxProfit(int* prices, int pricesSize) {
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int maxProfit = 0;
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int min = prices[0];
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for (int i = 1; i < pricesSize; i++) {
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if (prices[i] > min) {
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int profit = prices[i] - min;
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if (profit > maxProfit) {
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maxProfit = profit;
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}
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} else {
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min = prices[i];
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}
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}
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return maxProfit;
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}
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```

‎src/main/c/g0101_0200/s0124_binary_tree_maximum_path_sum/readme.md

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[![](https://img.shields.io/github/stars/LeetCode-in-C/LeetCode-in-C?label=Stars&style=flat-square)](https://github.com/LeetCode-in-C/LeetCode-in-C)
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[![](https://img.shields.io/github/forks/LeetCode-in-C/LeetCode-in-C?label=Fork%20me%20on%20GitHub%20&style=flat-square)](https://github.com/LeetCode-in-C/LeetCode-in-C/fork)
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## 124\. Binary Tree Maximum Path Sum
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Hard
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A **path** in a binary tree is a sequence of nodes where each pair of adjacent nodes in the sequence has an edge connecting them. A node can only appear in the sequence **at most once**. Note that the path does not need to pass through the root.
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The **path sum** of a path is the sum of the node's values in the path.
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Given the `root` of a binary tree, return _the maximum **path sum** of any **non-empty** path_.
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**Example 1:**
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![](https://assets.leetcode.com/uploads/2020/10/13/exx1.jpg)
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**Input:** root = [1,2,3]
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**Output:** 6
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**Explanation:** The optimal path is 2 -> 1 -> 3 with a path sum of 2 + 1 + 3 = 6.
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**Example 2:**
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![](https://assets.leetcode.com/uploads/2020/10/13/exx2.jpg)
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**Input:** root = [-10,9,20,null,null,15,7]
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**Output:** 42
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**Explanation:** The optimal path is 15 -> 20 -> 7 with a path sum of 15 + 20 + 7 = 42.
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**Constraints:**
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* The number of nodes in the tree is in the range <code>[1, 3 * 10<sup>4</sup>]</code>.
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* `-1000 <= Node.val <= 1000`
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## Solution
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```c
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#include <stdio.h>
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#include <limits.h>
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/**
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* Definition for a binary tree node.
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* struct TreeNode {
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* int val;
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* struct TreeNode *left;
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* struct TreeNode *right;
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* };
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*/
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// Initialize max to a very low value
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int max = INT_MIN;
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int helper(struct TreeNode* root) {
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if (root == NULL) {
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return 0;
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}
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// Recursively get the maximum path sum for left and right subtrees
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int left = helper(root->left);
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int right = helper(root->right);
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// Ensure negative values are replaced by 0
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left = (left > 0) ? left : 0;
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right = (right > 0) ? right : 0;
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// Calculate the current maximum path sum through this node
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int current = root->val + left + right;
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// Update global max if current is greater
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if (current > max) {
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max = current;
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}
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// Return the maximum path sum including this node and one of its subtrees
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return root->val + ((left > right) ? left : right);
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}
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int maxPathSum(struct TreeNode* root) {
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max = INT_MIN; // Reset max for each function call
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helper(root);
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return max;
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}
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// Helper function to create a new tree node
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struct TreeNode* createNode(int val) {
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struct TreeNode* node = (struct TreeNode*)malloc(sizeof(struct TreeNode));
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node->val = val;
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node->left = NULL;
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node->right = NULL;
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return node;
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}
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```

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