Codeforces Round 828 (Div. 3)

Solutions for Codeforces Round 828 (Div. 3) (contest 1744). 3/7 problems verified against sample I/O. Difficulty range: 800-2000.

7 items

Codeforces Round 828 (Div. 3)

Type: Div. 3 | Problems: 7 | Verified: 3/7 | Rating range: 800-2000 | Time: 28m 8s

Problem Name Rating Tags Solve Time Verified
A Number Replacement 800 greedy, implementation 8m 14s ✓
B Even-Odd Increments 800 implementation, math 2m 32s ✗
C Traffic Light 1000 binary-search, implementation, two-pointers 1m 42s ✓
D Divisibility by 2^n 1200 greedy, math, sortings 3m 22s ✓
E1 Divisible Numbers (easy version) 1500 brute-force, math, number-theory 6m 20s ✗
E2 Divisible Numbers (hard version) 1900 brute-force, math, number-theory 4m 4s ✗
F MEX vs MED 2000 math, two-pointers 1m 54s ✗
Practice › Codeforces Solutions › Codeforces Round 828 (Div. 3) ›

CF 1744F - MEX vs MED

Place the square in coordinates with (A(0,0)), (B(1,0)), (C(1,1)), (D(0,1)). Then (E) lies on (AB) and (F) on (BC) with (BE=BF). Writing (E=(x,0)) gives (BE=1-x), while (F=(1,y)) gives (BF=y), hence (y=1-x) and (F=(1,1-x)).
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Practice › Codeforces Solutions › Codeforces Round 828 (Div. 3) ›

CF 1744E2 - Divisible Numbers (hard version)

We are asked to find two numbers x and y inside given intervals such that their product is divisible by the product of two other numbers. Formally, given four integers a < c and b < d, we must find integers x and y satisfying a < x ≤ c, b < y ≤ d, and (x y) % (a b) == 0.
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Practice › Codeforces Solutions › Codeforces Round 828 (Div. 3) ›

CF 1744E1 - Divisible Numbers (easy version)

We are given four positive integers $a, b, c, d$ such that $a < c$ and $b < d$. The task is to find two numbers $x$ and $y$ satisfying $a < x le c$ and $b < y le d$ such that the product $x cdot y$ is divisible by $a cdot b$. If no such pair exists, we must return $-1 -1$.
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Practice › Codeforces Solutions › Codeforces Round 828 (Div. 3) ›

CF 1744A - Number Replacement

The task is to decide if a given array of integers can be mapped to a target string using a process where each distinct number in the array is assigned a single letter, and all occurrences of that number are replaced by that letter.
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Practice › Codeforces Solutions › Codeforces Round 828 (Div. 3) ›

CF 1744D - Divisibility by 2^n

We are given an array of positive integers, and we need to make the product of all elements divisible by $2^n$, where $n$ is the length of the array. We are allowed to multiply an element $ai$ by its own index $i$ exactly once per index.
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Practice › Codeforces Solutions › Codeforces Round 828 (Div. 3) ›

CF 1744B - Even-Odd Increments

The solution correctly identifies that the sawtooth function $(u) = u - lfloor u rfloor$ captures the fractional part of $x/y$ and that multiplying it by $y$ gives the remainder when $x$ is divided by $y$.
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Practice › Codeforces Solutions › Codeforces Round 828 (Div. 3) ›

CF 1744C - Traffic Light

The traffic light follows a cyclic pattern described by a string. If the string is "rggry", then after reaching the end it starts again from the beginning, producing an infinite sequence.
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