National Taiwan University NCPC Preliminary 2021

12 problems from National Taiwan University NCPC Preliminary 2021 (contest 103328), difficulty -. 11/12 solutions verified against sample I/O.

12 items

National Taiwan University NCPC Preliminary 2021

Special | 12 problems | 11/12 verified | Difficulty - | 12m 2s

# Problem Rating Tags Accepted Time ✓
A Traffic Jam 1m 11s ✓
B Apple Tree 54s ✓
C Perfect Cactus 51s ✓
D String Repetition 48s ✓
E Identity Subset 50s ✓
F Prime Gifts 1m 1s ✓
G AB Factory 49s ✓
H Mario Kart 2m 14s
I Road Reconstruction 56s ✓
J Hot Potato 48s ✓
K This is a Game 50s ✓
L Dungeon Matrix 50s ✓
Practice › Codeforces Solutions › National Taiwan University NCPC Preliminary 2021 ›

CF 103328H - Mario Kart

Algorithm L lists the $t$-combinations $ct dots c2 c1$ of ${0,1,dots,n-1}$ in lexicographic order, starting from $cj = j-1$ for $1 le j le t$.
codeforces competitive-programming Jul 3, 2026
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CF 103328A - Traffic Jam

We are given a long one-dimensional road and two types of moving entities on it: pedestrians who temporarily block a single fixed position during a time interval, and cars that continuously move along a segment from a starting position to an ending position starting at a given…
codeforces competitive-programming Jul 3, 2026
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CF 103328B - Apple Tree

We are given a tree with weighted nodes and weighted edges. Each node contains some number of apples. Each edge has a length.
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CF 103328K - This is a Game

We are given an array of positive integers. These numbers are not just static values, they are positions in a turn-based game where players repeatedly transform one chosen number.
codeforces competitive-programming Jul 3, 2026
Practice › Codeforces Solutions › National Taiwan University NCPC Preliminary 2021 ›

CF 103328L - Dungeon Matrix

We are given an $N times N$ grid where each cell stores one of two states, written as the characters L and R. We interpret this grid as a binary matrix, but there is a twist: L and R can be mapped to $0/1$ in two different ways, and both interpretations are valid.
codeforces competitive-programming Jul 3, 2026
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CF 103328I - Road Reconstruction

We are given a directed graph of cities where each road currently allows travel from one city to another. For every road, we are allowed to modify its status in exactly one of three ways: keep it as it is, reverse its direction by paying a given cost, or remove it entirely by…
codeforces competitive-programming Jul 3, 2026
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CF 103328J - Hot Potato

We are given a directed relationship graph among up to 20 players. Each player knows some other players, and this knowledge is not symmetric. A game starts with player 1 holding a token.
codeforces competitive-programming Jul 3, 2026
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CF 103328G - AB Factory

We are controlling a simple factory that can produce exactly one unit per day, and each day we must choose whether that unit is product A or product B.
codeforces competitive-programming Jul 3, 2026
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CF 103328F - Prime Gifts

We are given a prime number $p$, which represents both the number of children and a modular structure that will control how gifts can be evenly split. For each test case, Santa can buy a number of identical combo packages.
codeforces competitive-programming Jul 3, 2026
Practice › Codeforces Solutions › National Taiwan University NCPC Preliminary 2021 ›

CF 103328E - Identity Subset

We are given a prime number $P$ and a multiset $S$ containing exactly $P-1$ positive integers. Each number should be interpreted modulo $P$, and we are allowed to choose any non-empty multiset subset (so we can pick elements with multiplicity, respecting how many times they…
codeforces competitive-programming Jul 3, 2026
Practice › Codeforces Solutions › National Taiwan University NCPC Preliminary 2021 ›

CF 103328D - String Repetition

We are given a rooted tree with N nodes, where each node stores a single lowercase English letter. The root is fixed at node 1. For each query, we are given a target node u and a pattern string t.
codeforces competitive-programming Jul 3, 2026
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CF 103328C - Perfect Cactus

We are given a simple undirected graph that is guaranteed to be a cactus, meaning every edge belongs to at most one simple cycle. The task is to decide whether this graph is a perfect graph.
codeforces competitive-programming Jul 3, 2026