# Great Problems For Practice

[215. Kth Largest Element in an Array (Medium)](https://leetcode.com/problems/kth-largest-element-in-an-array/): Quick Select; Manually Implement Heap; API usage of `nth_element`, `make_heap`, `push_heap`, `pop_heap`

[1235. Maximum Profit in Job Scheduling (Hard)](https://leetcode.com/problems/maximum-profit-in-job-scheduling/): DP + Binary search because of sparse value (compared to continuous indexes)

[1830. Minimum Number of Operations to Make String Sorted (Hard)](https://leetcode.com/problems/minimum-number-of-operations-to-make-string-sorted/): permutation rank with duplicates

[472. Concatenated Words (Hard)](https://leetcode.com/problems/concatenated-words/): Trie + DP

## DP on Subsets OR Backtrack to Fill Buckets

* [698. Partition to K Equal Sum Subsets (Medium)](https://leetcode.com/problems/partition-to-k-equal-sum-subsets/)
* [473. Matchsticks to Square (Medium)](https://leetcode.com/problems/matchsticks-to-square/)
* [1723. Find Minimum Time to Finish All Jobs (Hard)](https://leetcode.com/problems/find-minimum-time-to-finish-all-jobs/)

## Geometry

* [478. Generate Random Point in a Circle (Medium)](https://leetcode.com/problems/generate-random-point-in-a-circle/)

## Trie + XOR

* [421. Maximum XOR of Two Numbers in an Array (Medium)](https://leetcode.com/problems/maximum-xor-of-two-numbers-in-an-array/)
* [1707. Maximum XOR With an Element From Array (Hard)](https://leetcode.com/problems/maximum-xor-with-an-element-from-array/)
* [1803. Count Pairs With XOR in a Range (Hard)](https://leetcode.com/problems/count-pairs-with-xor-in-a-range/)

## BIT (Binary Index Tree) or Segment Tree

* [307. Range Sum Query - Mutable (Medium)](https://leetcode.com/problems/range-sum-query-mutable/)

## Backtracking

* [51. N-Queens (Hard)](https://leetcode.com/problems/n-queens/)
* [698. Partition to K Equal Sum Subsets (Medium)](https://leetcode.com/problems/partition-to-k-equal-sum-subsets/)
* [473. Matchsticks to Square (Medium)](https://leetcode.com/problems/matchsticks-to-square/)

## Stack operation on string

* [1003. Check If Word Is Valid After Substitutions (Medium)](https://leetcode.com/problems/check-if-word-is-valid-after-substitutions/)
* [1209. Remove All Adjacent Duplicates in String II (Medium)](https://leetcode.com/problems/remove-all-adjacent-duplicates-in-string-ii/)

## Permutation

* [60. Permutation Sequence (Hard)](https://leetcode.com/problems/permutation-sequence/)
* [31. Next Permutation (Medium)](https://leetcode.com/problems/next-permutation/)

## Mono Stack / Mono Deque

* [907. Sum of Subarray Minimums (Medium)](https://leetcode.com/problems/sum-of-subarray-minimums/)

## Sorting

* [912. Sort an Array (Medium)](https://leetcode.com/problems/sort-an-array/)

## Binary Indexed Tree

* [307. Range Sum Query - Mutable (Medium)](https://leetcode.com/problems/range-sum-query-mutable)