README.md

leet_4_Code

My Leetcode problem solution in C++

LeetCode Topics

String

Problem Name	Difficulty
0049-group-anagrams	Medium
0125-valid-palindrome	Easy
0131-palindrome-partitioning	Medium
0132-palindrome-partitioning-ii	Hard
0316-remove-duplicate-letters	Medium
0680-valid-palindrome-ii	Easy
1081-smallest-subsequence-of-distinct-characters	Medium
1358-number-of-substrings-containing-all-three-characters	Medium
1967-number-of-strings-that-appear-as-substrings-in-word	Easy
3014-minimum-number-of-pushes-to-type-word-i	Easy
3016-minimum-number-of-pushes-to-type-word-ii	Medium
3499-maximize-active-section-with-trade-i	Medium
3501-maximize-active-section-with-trade-ii	Hard
3517-smallest-palindromic-rearrangement-i	Medium
3518-smallest-palindromic-rearrangement-ii	Hard
3756-concatenate-non-zero-digits-and-multiply-by-sum-ii	Medium

Dynamic Programming

Problem Name	Difficulty
0131-palindrome-partitioning	Medium
0132-palindrome-partitioning-ii	Hard
1301-number-of-paths-with-max-score	Hard
3336-find-the-number-of-subsequences-with-equal-gcd	Hard
3534-path-existence-queries-in-a-graph-ii	Hard
3620-network-recovery-pathways	Hard
3699-number-of-zigzag-arrays-i	Hard
3700-number-of-zigzag-arrays-ii	Hard

Backtracking

Problem Name	Difficulty
0039-combination-sum	Medium
0040-combination-sum-ii	Medium
0113-path-sum-ii	Medium
0131-palindrome-partitioning	Medium

Array

Problem Name	Difficulty
0001-two-sum	Easy
0015-3sum	Medium
0034-find-first-and-last-position-of-element-in-sorted-array	Medium
0039-combination-sum	Medium
0040-combination-sum-ii	Medium
0049-group-anagrams	Medium
0084-largest-rectangle-in-histogram	Hard
0105-construct-binary-tree-from-preorder-and-inorder-traversal	Medium
0128-longest-consecutive-sequence	Medium
0150-evaluate-reverse-polish-notation	Medium
0167-two-sum-ii-input-array-is-sorted	Medium
0238-product-of-array-except-self	Medium
0347-top-k-frequent-elements	Medium
0628-maximum-product-of-three-numbers	Easy
0739-daily-temperatures	Medium
0875-koko-eating-bananas	Medium
1011-capacity-to-ship-packages-within-d-days	Medium
1110-delete-nodes-and-return-forest	Medium
1260-shift-2d-grid	Easy
1288-remove-covered-intervals	Medium
1301-number-of-paths-with-max-score	Hard
1464-maximum-product-of-two-elements-in-an-array	Easy
1846-maximum-element-after-decreasing-and-rearranging	Medium
1967-number-of-strings-that-appear-as-substrings-in-word	Easy
1979-find-greatest-common-divisor-of-array	Easy
2447-number-of-subarrays-with-gcd-equal-to-k	Medium
2812-find-the-safest-path-in-a-grid	Medium
3020-find-the-maximum-number-of-elements-in-subset	Medium
3286-find-a-safe-walk-through-a-grid	Medium
3312-sorted-gcd-pair-queries	Hard
3336-find-the-number-of-subsequences-with-equal-gcd	Hard
3501-maximize-active-section-with-trade-ii	Hard
3513-number-of-unique-xor-triplets-i	Medium
3514-number-of-unique-xor-triplets-ii	Medium
3534-path-existence-queries-in-a-graph-ii	Hard
3620-network-recovery-pathways	Hard
3737-count-subarrays-with-majority-element-i	Medium
3739-count-subarrays-with-majority-element-ii	Hard
3867-sum-of-gcd-of-formed-pairs	Medium

Hash Table

Problem Name	Difficulty
0001-two-sum	Easy
0049-group-anagrams	Medium
0105-construct-binary-tree-from-preorder-and-inorder-traversal	Medium
0128-longest-consecutive-sequence	Medium
0347-top-k-frequent-elements	Medium
1110-delete-nodes-and-return-forest	Medium
1358-number-of-substrings-containing-all-three-characters	Medium
3016-minimum-number-of-pushes-to-type-word-ii	Medium
3020-find-the-maximum-number-of-elements-in-subset	Medium
3312-sorted-gcd-pair-queries	Hard
3518-smallest-palindromic-rearrangement-ii	Hard
3737-count-subarrays-with-majority-element-i	Medium
3739-count-subarrays-with-majority-element-ii	Hard

Prefix Sum

Problem Name	Difficulty
0238-product-of-array-except-self	Medium
3312-sorted-gcd-pair-queries	Hard
3699-number-of-zigzag-arrays-i	Hard
3737-count-subarrays-with-majority-element-i	Medium
3739-count-subarrays-with-majority-element-ii	Hard
3756-concatenate-non-zero-digits-and-multiply-by-sum-ii	Medium

Sorting

Problem Name	Difficulty
0015-3sum	Medium
0049-group-anagrams	Medium
0347-top-k-frequent-elements	Medium
0628-maximum-product-of-three-numbers	Easy
1288-remove-covered-intervals	Medium
1464-maximum-product-of-two-elements-in-an-array	Easy
1846-maximum-element-after-decreasing-and-rearranging	Medium
3016-minimum-number-of-pushes-to-type-word-ii	Medium
3517-smallest-palindromic-rearrangement-i	Medium
3534-path-existence-queries-in-a-graph-ii	Hard
3536-maximum-product-of-two-digits	Easy
3867-sum-of-gcd-of-formed-pairs	Medium

Divide and Conquer

Problem Name	Difficulty
0105-construct-binary-tree-from-preorder-and-inorder-traversal	Medium
0347-top-k-frequent-elements	Medium
3737-count-subarrays-with-majority-element-i	Medium
3739-count-subarrays-with-majority-element-ii	Hard

Heap (Priority Queue)

Problem Name	Difficulty
0347-top-k-frequent-elements	Medium
1464-maximum-product-of-two-elements-in-an-array	Easy
2812-find-the-safest-path-in-a-grid	Medium
3286-find-a-safe-walk-through-a-grid	Medium
3620-network-recovery-pathways	Hard

Bucket Sort

Problem Name	Difficulty
0347-top-k-frequent-elements	Medium

Counting

Problem Name	Difficulty
0347-top-k-frequent-elements	Medium
3016-minimum-number-of-pushes-to-type-word-ii	Medium
3312-sorted-gcd-pair-queries	Hard
3518-smallest-palindromic-rearrangement-ii	Hard
3737-count-subarrays-with-majority-element-i	Medium

Quickselect

Problem Name	Difficulty
0347-top-k-frequent-elements	Medium

Math

Problem Name	Difficulty
0150-evaluate-reverse-polish-notation	Medium
0628-maximum-product-of-three-numbers	Easy
1979-find-greatest-common-divisor-of-array	Easy
2447-number-of-subarrays-with-gcd-equal-to-k	Medium
3014-minimum-number-of-pushes-to-type-word-i	Easy
3312-sorted-gcd-pair-queries	Hard
3336-find-the-number-of-subsequences-with-equal-gcd	Hard
3513-number-of-unique-xor-triplets-i	Medium
3514-number-of-unique-xor-triplets-ii	Medium
3518-smallest-palindromic-rearrangement-ii	Hard
3536-maximum-product-of-two-digits	Easy
3700-number-of-zigzag-arrays-ii	Hard
3754-concatenate-non-zero-digits-and-multiply-by-sum-i	Easy
3756-concatenate-non-zero-digits-and-multiply-by-sum-ii	Medium
3867-sum-of-gcd-of-formed-pairs	Medium

Segment Tree

Problem Name	Difficulty
3501-maximize-active-section-with-trade-ii	Hard
3737-count-subarrays-with-majority-element-i	Medium
3739-count-subarrays-with-majority-element-ii	Hard

Merge Sort

Problem Name	Difficulty
3737-count-subarrays-with-majority-element-i	Medium
3739-count-subarrays-with-majority-element-ii	Hard

Enumeration

Problem Name	Difficulty
3020-find-the-maximum-number-of-elements-in-subset	Medium
3499-maximize-active-section-with-trade-i	Medium
3514-number-of-unique-xor-triplets-ii	Medium

Greedy

Problem Name	Difficulty
0316-remove-duplicate-letters	Medium
0680-valid-palindrome-ii	Easy
1081-smallest-subsequence-of-distinct-characters	Medium
1846-maximum-element-after-decreasing-and-rearranging	Medium
3014-minimum-number-of-pushes-to-type-word-i	Easy
3016-minimum-number-of-pushes-to-type-word-ii	Medium
3534-path-existence-queries-in-a-graph-ii	Hard

Union-Find

Problem Name	Difficulty
0128-longest-consecutive-sequence	Medium
2492-minimum-score-of-a-path-between-two-cities	Medium
2685-count-the-number-of-complete-components	Medium
2812-find-the-safest-path-in-a-grid	Medium

Two Pointers

Problem Name	Difficulty
0015-3sum	Medium
0125-valid-palindrome	Easy
0167-two-sum-ii-input-array-is-sorted	Medium
0680-valid-palindrome-ii	Easy
3534-path-existence-queries-in-a-graph-ii	Hard
3867-sum-of-gcd-of-formed-pairs	Medium

Binary Search

Problem Name	Difficulty
0034-find-first-and-last-position-of-element-in-sorted-array	Medium
0167-two-sum-ii-input-array-is-sorted	Medium
0875-koko-eating-bananas	Medium
1011-capacity-to-ship-packages-within-d-days	Medium
2812-find-the-safest-path-in-a-grid	Medium
3312-sorted-gcd-pair-queries	Hard
3501-maximize-active-section-with-trade-ii	Hard
3534-path-existence-queries-in-a-graph-ii	Hard
3620-network-recovery-pathways	Hard

Sliding Window

Problem Name	Difficulty
1358-number-of-substrings-containing-all-three-characters	Medium

Breadth-First Search

Problem Name	Difficulty
0112-path-sum	Easy
0199-binary-tree-right-side-view	Medium
0958-check-completeness-of-a-binary-tree	Medium
2492-minimum-score-of-a-path-between-two-cities	Medium
2685-count-the-number-of-complete-components	Medium
2812-find-the-safest-path-in-a-grid	Medium
3286-find-a-safe-walk-through-a-grid	Medium

Matrix

Problem Name	Difficulty
1260-shift-2d-grid	Easy
1301-number-of-paths-with-max-score	Hard
2812-find-the-safest-path-in-a-grid	Medium
3286-find-a-safe-walk-through-a-grid	Medium

Tree

Problem Name	Difficulty
0105-construct-binary-tree-from-preorder-and-inorder-traversal	Medium
0112-path-sum	Easy
0113-path-sum-ii	Medium
0199-binary-tree-right-side-view	Medium
0236-lowest-common-ancestor-of-a-binary-tree	Medium
0814-binary-tree-pruning	Medium
0958-check-completeness-of-a-binary-tree	Medium
1110-delete-nodes-and-return-forest	Medium

Depth-First Search

Problem Name	Difficulty
0112-path-sum	Easy
0113-path-sum-ii	Medium
0199-binary-tree-right-side-view	Medium
0236-lowest-common-ancestor-of-a-binary-tree	Medium
0814-binary-tree-pruning	Medium
1110-delete-nodes-and-return-forest	Medium
2492-minimum-score-of-a-path-between-two-cities	Medium
2685-count-the-number-of-complete-components	Medium

Binary Tree

Problem Name	Difficulty
0105-construct-binary-tree-from-preorder-and-inorder-traversal	Medium
0112-path-sum	Easy
0113-path-sum-ii	Medium
0199-binary-tree-right-side-view	Medium
0236-lowest-common-ancestor-of-a-binary-tree	Medium
0814-binary-tree-pruning	Medium
0958-check-completeness-of-a-binary-tree	Medium
1110-delete-nodes-and-return-forest	Medium

Graph Theory

Problem Name	Difficulty
2492-minimum-score-of-a-path-between-two-cities	Medium
2685-count-the-number-of-complete-components	Medium
3286-find-a-safe-walk-through-a-grid	Medium
3534-path-existence-queries-in-a-graph-ii	Hard
3620-network-recovery-pathways	Hard

Shortest Path

Problem Name	Difficulty
3286-find-a-safe-walk-through-a-grid	Medium
3620-network-recovery-pathways	Hard

Database

Problem Name	Difficulty
0177-nth-highest-salary	Medium
0620-not-boring-movies	Easy
0627-swap-sex-of-employees	Easy
1050-actors-and-directors-who-cooperated-at-least-three-times	Easy

Topological Sort

Problem Name	Difficulty
3620-network-recovery-pathways	Hard

Bit Manipulation

Problem Name	Difficulty
3513-number-of-unique-xor-triplets-i	Medium
3514-number-of-unique-xor-triplets-ii	Medium
3534-path-existence-queries-in-a-graph-ii	Hard

Number Theory

Problem Name	Difficulty
1979-find-greatest-common-divisor-of-array	Easy
2447-number-of-subarrays-with-gcd-equal-to-k	Medium
3312-sorted-gcd-pair-queries	Hard
3336-find-the-number-of-subsequences-with-equal-gcd	Hard
3867-sum-of-gcd-of-formed-pairs	Medium

Stack

Problem Name	Difficulty
0084-largest-rectangle-in-histogram	Hard
0150-evaluate-reverse-polish-notation	Medium
0316-remove-duplicate-letters	Medium
0739-daily-temperatures	Medium
1081-smallest-subsequence-of-distinct-characters	Medium

Simulation

Problem Name	Difficulty
1260-shift-2d-grid	Easy
3867-sum-of-gcd-of-formed-pairs	Medium

Monotonic Stack

Problem Name	Difficulty
0084-largest-rectangle-in-histogram	Hard
0316-remove-duplicate-letters	Medium
0739-daily-temperatures	Medium
1081-smallest-subsequence-of-distinct-characters	Medium

Combinatorics

Problem Name	Difficulty
3312-sorted-gcd-pair-queries	Hard
3518-smallest-palindromic-rearrangement-ii	Hard

Counting Sort

Problem Name	Difficulty
3517-smallest-palindromic-rearrangement-i	Medium