Codeforces Round 171 (Div. 2)

5 problems from Codeforces Round 171 (Div. 2) (contest 279), difficulty 1400-2200. 4/5 solutions verified against sample I/O.

5 items

Codeforces Round 171 (Div. 2)

Div. 2 | 5 problems | 4/5 verified | Difficulty 1400-2200 | 11m 10s

# Problem Rating Tags Accepted Time ✓
A Point on Spiral 1400 brute-force, geometry, implementation 5,915 1m 20s ✓
B Books 1400 binary-search, brute-force, implementation 72,369 1m 38s ✓
C Ladder 1700 dp, implementation, two-pointers 8,923 1m 27s ✓
D The Minimum Number of Variables 2200 bitmasks, dp 855 2m 37s
E Beautiful Decomposition 1900 dp, games, greedy 1,603 4m 8s ✓
Practice › Codeforces Solutions › Codeforces Round 171 (Div. 2) ›

CF 279A - Point on Spiral

We are asked to count how many times a horse must turn when moving along a spiral from the origin to a target point $(x, y)$.
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Practice › Codeforces Solutions › Codeforces Round 171 (Div. 2) ›

CF 279B - Books

We have a row of books, and the time needed to read each book is known. Valera may start from any position and then read consecutive books to the right. He cannot skip books, and he only starts a book if he has enough remaining time to finish it completely.
codeforces competitive-programming binary-search brute-force implementation two-pointers Jun 5, 2026
Practice › Codeforces Solutions › Codeforces Round 171 (Div. 2) ›

CF 279E - Beautiful Decomposition

A beautiful number is any power of two with either sign. In other words, every summand must be one of $$pm 2^0, pm 2^1, pm 2^2,dots$$ We are given a positive integer $n$, but not in decimal form.
codeforces competitive-programming dp games greedy number-theory Jun 5, 2026
Practice › Codeforces Solutions › Codeforces Round 171 (Div. 2) ›

CF 279D - The Minimum Number of Variables

We are given a sequence of distinct positive integers. The sequence is not arbitrary, it must be generated step by step using a collection of variables. At the beginning every variable contains 0. The first value of the sequence is special.
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Practice › Codeforces Solutions › Codeforces Round 171 (Div. 2) ›

CF 279C - Ladder

We are given a one-dimensional array of integers and a list of queries, each specifying a contiguous subsegment of the array. For every query, we need to determine whether the subsegment forms a "ladder.
codeforces competitive-programming dp implementation two-pointers Jun 5, 2026