---
# System prepended metadata

title: LeetCode 75
tags: [problems]

---

###### tags: `problems`
# LeetCode 75
https://leetcode.com/study-plan/leetcode-75/?progress=1zoewgt

## Day 1 Prefix Sum
- [1480. Running Sum of 1d Array](https://leetcode.com/problems/running-sum-of-1d-array/) [[Array](https://leetcode.com/tag/array)]
- [724. Find Pivot Index](https://leetcode.com/problems/find-pivot-index/) [[Array](https://leetcode.com/tag/array)]
## Day 2 String
- [205. Isomorphic Strings](https://leetcode.com/problems/isomorphic-strings/) [[Hash Table](https://leetcode.com/tag/hash-table)]
- [392. Is Subsequence](https://leetcode.com/problems/is-subsequence/) [[Two Pointers](https://leetcode.com/tag/two-pointers)]
## Day 3 Linked List
- [21. Merge Two Sorted Lists](https://leetcode.com/problems/merge-two-sorted-lists/) [[Linked List](https://leetcode.com/tag/linked-list)]
- [206. Reverse Linked List](https://leetcode.com/problems/reverse-linked-list/) [[Linked List](https://leetcode.com/tag/linked-list)]
## Day 4 Linked List
- [876. Middle of the Linked List](https://leetcode.com/problems/middle-of-the-linked-list/) [[Linked List](https://leetcode.com/tag/linked-list)]
- [142. Linked List Cycle II](https://leetcode.com/problems/linked-list-cycle-ii/) [[Hash Table](https://leetcode.com/tag/hash-table)]
## Day 5 Greedy
- [121. Best Time to Buy and Sell Stock](https://leetcode.com/problems/best-time-to-buy-and-sell-stock/) [[Array](https://leetcode.com/tag/array)]
- [409. Longest Palindrome](https://leetcode.com/problems/longest-palindrome/) [[Hash Table](https://leetcode.com/tag/hash-table)]
## Day 6 Tree
- [589. N-ary Tree Preorder Traversal](https://leetcode.com/problems/n-ary-tree-preorder-traversal/) [[Stack](https://leetcode.com/tag/stack)]
- [102. Binary Tree Level Order Traversal](https://leetcode.com/problems/binary-tree-level-order-traversal/) [[Tree](https://leetcode.com/tag/tree)]
## Day 7 Binary Search
- [704. Binary Search](https://leetcode.com/problems/binary-search/) [[Array](https://leetcode.com/tag/array)]
- [278. First Bad Version](https://leetcode.com/problems/first-bad-version/) [[Binary Search](https://leetcode.com/tag/binary-search)]
## Day 8 Binary Search Tree
- [98. Validate Binary Search Tree](https://leetcode.com/problems/validate-binary-search-tree/) [[Tree](https://leetcode.com/tag/tree)]
- [235. Lowest Common Ancestor of a Binary Search Tree](https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-search-tree/) [[Tree](https://leetcode.com/tag/tree)]
## Day 9 Graph/BFS/DFS
- [733. Flood Fill](https://leetcode.com/problems/flood-fill/) [[Array](https://leetcode.com/tag/array)]
- [200. Number of Islands](https://leetcode.com/problems/number-of-islands/) [[Array](https://leetcode.com/tag/array)]
## Day 10 Dynamic Programming
- [509. Fibonacci Number](https://leetcode.com/problems/fibonacci-number/) [[Math](https://leetcode.com/tag/math)]
- [70. Climbing Stairs](https://leetcode.com/problems/climbing-stairs/) [[Math](https://leetcode.com/tag/math)]
## Day 11 Dynamic Programming
- [746. Min Cost Climbing Stairs](https://leetcode.com/problems/min-cost-climbing-stairs/) [[Array](https://leetcode.com/tag/array)]
- [62. Unique Paths](https://leetcode.com/problems/unique-paths/) [[Math](https://leetcode.com/tag/math)]
## Day 12 Sliding Window/Two Pointer
- [438. Find All Anagrams in a String](https://leetcode.com/problems/find-all-anagrams-in-a-string/) [[Hash Table](https://leetcode.com/tag/hash-table)]
- [424. Longest Repeating Character Replacement](https://leetcode.com/problems/longest-repeating-character-replacement/) [[Hash Table](https://leetcode.com/tag/hash-table)]
## Day 13 Hashmap
- [1. Two Sum](https://leetcode.com/problems/two-sum/) [[Array](https://leetcode.com/tag/array)]
- [299. Bulls and Cows](https://leetcode.com/problems/bulls-and-cows/) [[Hash Table](https://leetcode.com/tag/hash-table)]
## Day 14 Stack
- [844. Backspace String Compare](https://leetcode.com/problems/backspace-string-compare/) [[Two Pointers](https://leetcode.com/tag/two-pointers)]
- [394. Decode String](https://leetcode.com/problems/decode-string/) [[String](https://leetcode.com/tag/string)]
## Day 15 Heap
- [1046. Last Stone Weight](https://leetcode.com/problems/last-stone-weight/) [[Array](https://leetcode.com/tag/array)]
- [692. Top K Frequent Words](https://leetcode.com/problems/top-k-frequent-words/) [[Hash Table](https://leetcode.com/tag/hash-table)]
