Codeforces Round 257 (Div. 1)

5 problems from Codeforces Round 257 (Div. 1) (contest 449), difficulty 1700-2900. 3/5 solutions verified against sample I/O.

5 items

Codeforces Round 257 (Div. 1)

Div. 1 | 5 problems | 3/5 verified | Difficulty 1700-2900 | 9m 38s

# Problem Rating Tags Accepted Time ✓
A Jzzhu and Chocolate 1700 greedy, math 4,126 2m 1s ✓
B Jzzhu and Cities 2000 graphs, greedy, shortest-paths 10,588 1m 26s ✓
C Jzzhu and Apples 2500 constructive-algorithms, number-theory 2,527 1m 44s
D Jzzhu and Numbers 2400 bitmasks, combinatorics, dp 6,134 1m 54s ✓
E Jzzhu and Squares 2900 dp, math, number-theory 305 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.
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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.
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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.
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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