Codeforces Round 142 (Div. 1)

5 problems from Codeforces Round 142 (Div. 1) (contest 229), difficulty 1500-2600. 5/5 solutions verified against sample I/O.

5 items

Codeforces Round 142 (Div. 1)

Div. 1 | 5 problems | 5/5 verified | Difficulty 1500-2600 | 10m 59s

# Problem Rating Tags Accepted Time ✓
A Shifts 1500 brute-force, two-pointers 3,754 1m 34s ✓
B Planets 1700 binary-search, data-structures, graphs 5,785 1m 37s ✓
C Triangles 1900 combinatorics, graphs, math 1,782 2m 5s ✓
D Towers 2100 dp, greedy, two-pointers 2,618 2m 55s ✓
E Gifts 2600 combinatorics, dp, math 525 2m 48s ✓
Practice › Codeforces Solutions › Codeforces Round 142 (Div. 1) ›

CF 229A - Shifts

We have a binary matrix where each row can be rotated cyclically. A left rotation moves every element one position left and wraps the first element to the end. A right rotation does the opposite.
codeforces competitive-programming brute-force two-pointers May 29, 2026
Practice › Codeforces Solutions › Codeforces Round 142 (Div. 1) ›

CF 229B - Planets

We are given an undirected weighted graph of planets connected by stargates. Jack starts on planet 1 at time 0 and wants to reach planet n as early as possible. Moving through a stargate takes a fixed positive amount of time. The unusual part is the waiting rule.
codeforces competitive-programming binary-search data-structures graphs shortest-paths May 29, 2026
Practice › Codeforces Solutions › Codeforces Round 142 (Div. 1) ›

CF 229C - Triangles

We start with a complete undirected graph on n vertices. Every pair of vertices has exactly one edge between them. Alice keeps m of those edges, and Bob receives all remaining edges.
codeforces competitive-programming combinatorics graphs math May 29, 2026
Practice › Codeforces Solutions › Codeforces Round 142 (Div. 1) ›

CF 229D - Towers

We are given a sequence of towers standing in a straight line, where the height of the tower at position i is h[i]. The goal is to make the sequence non-decreasing from left to right using a set of allowed operations.
codeforces competitive-programming dp greedy two-pointers May 29, 2026
Practice › Codeforces Solutions › Codeforces Round 142 (Div. 1) ›

CF 229E - Gifts

We are given a collection of gifts, each with a name and a set of distinct prices. Some names may appear multiple times, each with different prices. The old man can request exactly n gifts, specifying only names.
codeforces competitive-programming combinatorics dp math probabilities May 29, 2026