Optimization and Strategy Problems on Sequences and Grids
Resource Redistribution with Asymmetric Operations
Given a sequence (a) of length (n) and two positive integers (x, y) where (y \le x). You may repeatedly pick two elements and transfer resources: subtract (x) from one and add (y) to the other, provided the first remains non‑negative. Determine the maximum possible value of any element after op ...
Posted on Tue, 09 Jun 2026 17:33:25 +0000 by obesechicken13
Maximum Sum Divisible by Three
Given an integer array nums, find and return the maximum sum of elements that is divisible by three.
Examples
Example 1:
Input: nums = [3,6,5,1,8]
Output: 18
Explanation: Choose numbers 3, 6, 1, and 8. Their sum is 18 (the maximum sum divisible by three).
Example 2:
Input: nums = [4]
Output: 0
Explanation: 4 is not divisible by 3, so no number ...
Posted on Tue, 02 Jun 2026 17:22:57 +0000 by JamesThePanda
Contest Problem Solutions: Factorization, Rays, String Construction, and Tree Partitioning
Factorization into Factorial Divisors
Given integers (n) and (m) where (1 \le m \le n!) and (n \le 20), decompose (m) into a sum of at most (n) divisors of (n!). A solution is guaranteed to exist.
Define a sequence (d_i = \frac{n!}{i!}) for (i) from 1 to (n). By iterating downwards from (i=n) to (1) and greedily subtracting the largest possible ...
Posted on Mon, 01 Jun 2026 17:41:27 +0000 by taldos
Solutions for the SXJ202507250900 Simulation Contest
Problem 1: Dumpling Purchase Optimization
The problem reduces to a daily deciison: buy dumplings at the current price or rely on an earlier purchase plus storage cost. The total expense for day i if we buy on day j ≤ i is price[j] + c*(i - j). This can be rewritten as (price[j] - c*j) + c*i. Thus we can maintain the minimum value of price[j] - ...
Posted on Sat, 23 May 2026 19:20:05 +0000 by d_barszczak
AtCoder ABC 069 Solutions
Problem A - 4
Question
With (n) horizontal lines and (m) vertical lines drawn on a plane, how many axis-aligned rectangles are formed that contain no interior lines?
Solution
Consider each dimension independent.
Along any straight line, (n) distinct points partition the line into (n - 1) segments. These segments serve as the edges of our rectan ...
Posted on Fri, 22 May 2026 20:05:22 +0000 by suresh1
Dynamic Programming on Increasing and Decreasing Sequences
Consider a sequence $A = (a_1, a_2, \dots, a_n)$. We want to partition $A$ into contiguous subsequences, and then arrange these subsequences to form a new sequence $f_1, f_2, \dots, f_k$. Each contiguous subsequence $f_1, \dots, f_p$ must satisfy either $f_1 \le f_2 \le \dots \le f_p$ or $f_1 \ge f_2 \ge \dots \ge f_p$. The cost associated with ...
Posted on Tue, 19 May 2026 12:41:33 +0000 by thedream
Contest Round 33 Editorial: Emphasis on Algorithmic Thinking
A. Word Rearrangement
This is a straightforward problem requiring only basic input/output handling.
w1, w2 = input().split()
print(w2)
print(w1)
B. Cooking Tangyuan
The key idea is to simulate the process of using packages to fulfill cooking rounds. Each package contributes a fixed number of tangyuan, and excess can carry over.
n, x, k = map(i ...
Posted on Sun, 17 May 2026 14:48:21 +0000 by Fjerpje
Interval Dynamic Programming: Classic Problems and Solutions
Progress: Dynamic Programming - Linear DP, Knapsack, Interval DP
Merging Palindromic Substrings
Tags: Interval DP
Foundation - Longest Palindromic Substring
Problem: Given a string (S), find the length of its longest palindromic substring.
Approach: A longer palindrome can always be constructed by adding identical characters to both ends of a s ...
Posted on Thu, 14 May 2026 05:56:34 +0000 by sb
Greedy Algorithm: Minimum Cameras to Monitor a Binary Tree
Greedy Algorithm: Minimum Cameras to Monitor a Binary Tree
Given a binary tree, we need to place cameras on nodes such that every node in the tree is monitored. A camera placed on a node monitors itself, its parenet, and its immediate children. Determine the minimum number of cameras required.
Approach
We can solve this problem using a greedy a ...
Posted on Wed, 13 May 2026 14:26:44 +0000 by TPerez
LLVM RAGreedy Register Allocator Internals: Allocation, Eviction, Splitting, and Spilling Mechanics
Core Core Data Structures
Structure
Purpose
LiveIntervals
Stores live ranges for every virtual register
LiveRegMatrix
Tracks physical-to-virtual mappings and interference
PriorityQueue
Heap-based queue ordered by Priority
VirtRegMap
Final virtual → physical assignment
EvictAdvisor
Decides whether evicting an existing allocation i ...
Posted on Wed, 13 May 2026 03:59:11 +0000 by dnice