Codeforces Round 257 (Div. 1)

Solutions for Codeforces Round 257 (Div. 1) (contest 449). 3/5 problems verified against sample I/O. Difficulty range: 1700-2900.

5 items

Codeforces Round 257 (Div. 1)

Type: Div. 1 | Problems: 5 | Verified: 3/5 | Rating range: 1700-2900 | Time: 9m 38s

Problem Name Rating Tags Solve Time Verified
A Jzzhu and Chocolate 1700 greedy, math 2m 1s ✓
B Jzzhu and Cities 2000 graphs, greedy, shortest-paths 1m 26s ✓
C Jzzhu and Apples 2500 constructive-algorithms, number-theory 1m 44s ✗
D Jzzhu and Numbers 2400 bitmasks, combinatorics, dp 1m 54s ✓
E Jzzhu and Squares 2900 dp, math, number-theory 2m 33s ✗
Practice › Codeforces Solutions › Codeforces Round 257 (Div. 1) ›

CF 449A - Jzzhu and Chocolate

We have an $n times m$ chocolate bar made of unit squares. A cut is either horizontal or vertical, must follow grid lines, must lie strictly inside the chocolate, and cannot duplicate a previous cut.
codeforces competitive-programming greedy math May 30, 2026
Practice › Codeforces Solutions › Codeforces Round 257 (Div. 1) ›

CF 449B - Jzzhu and Cities

We are given an undirected weighted graph representing cities and roads. City 1 is the capital. In addition to normal roads, there are special train routes that connect the capital directly to some city. The government wants to close as many train routes as possible.
codeforces competitive-programming graphs greedy shortest-paths May 30, 2026
Practice › Codeforces Solutions › Codeforces Round 257 (Div. 1) ›

CF 449C - Jzzhu and Apples

We have apples numbered from 1 to n. We want to create as many disjoint pairs as possible such that the two numbers in each pair have greatest common divisor greater than 1. Each apple can appear in at most one pair.
codeforces competitive-programming constructive-algorithms number-theory May 30, 2026
Practice › Codeforces Solutions › Codeforces Round 257 (Div. 1) ›

CF 449D - Jzzhu and Numbers

We are given an array of n non-negative integers. A group is any non-empty subset of array indices. For a chosen group, we take the bitwise AND of all values at those indices. The task is to count how many non-empty groups have bitwise AND equal to 0.
codeforces competitive-programming bitmasks combinatorics dp May 30, 2026
Practice › Codeforces Solutions › Codeforces Round 257 (Div. 1) ›

CF 449E - Jzzhu and Squares

We have all lattice points inside a rectangle of size $n times m$. Any square whose four vertices are lattice points is allowed, even if it is rotated. For every such square, we look at the unit grid cells completely contained inside it. Each contained unit cell receives one dot.
codeforces competitive-programming dp math number-theory May 30, 2026