Semana i 2019

11 problems from Semana i 2019 (contest 102409), difficulty -. 10/11 solutions verified against sample I/O.

11 items

Semana i 2019

Special | 11 problems | 10/11 verified | Difficulty - | 1h 5m

#	Problem	Rating	Tags	Accepted	Time	✓
A	Easy Math				2m 13s	✓
B	Xor Sums				10m 36s	✓
C	Xor in Tree				6m 57s	✓
D	Lottery Ticket				13m 28s	✓
E	Googles wants to maximize				5m 43s
F	Ironical Solution 1				2m 26s	✓
G	Ironical Solution 2				2m 58s	✓
H	Maximizing Coins				11m 48s	✓
I	Thanos's snap				2m 30s	✓
J	Best division				2m 12s	✓
K	Lending Woes				4m 33s	✓

Practice › Codeforces Solutions › Semana i 2019 ›

CF 102409H - Maximizing Coins

We have a sequence of rooms numbered from 1 to (N). Room (N) is the destination and contains no coins. From room (i), Diego may jump to any later room whose index is at most (i+ki). When he visits a room (i<N), he collects its (ci) coins.

Practice › Codeforces Solutions › Semana i 2019 ›

CF 102409D - Lottery Ticket

We have tickets numbered from 1 through (N), arranged in increasing order on a circle. Diego starts at ticket (S). From the current ticket, the process moves exactly (K) surviving tickets to the right and removes the ticket where it lands.

Practice › Codeforces Solutions › Semana i 2019 ›

CF 102409K - Lending Woes

The original loans do not matter individually once we know each person's net position. For every loan a b c, person a has given away c, while person b has received c.

Practice › Codeforces Solutions › Semana i 2019 ›

CF 102409J - Best division

There are (N-1) legal cutting positions inside a chocolate bar of length (L). Adding the two endpoints (0) and (L), we have (N+1) positions that describe (N) elementary pieces. We must choose exactly three of the interior positions, producing four contiguous pieces.

Practice › Codeforces Solutions › Semana i 2019 ›

CF 102409I - Thanos's snap

There are exactly (N=5{,}000{,}000) people in Diegopolis. Each person independently survives the snap with probability (1/2). Let (X) be the number of survivors, so (X) follows a binomial distribution with parameters (N) and (1/2).

Practice › Codeforces Solutions › Semana i 2019 ›

CF 102409E - Googles wants to maximize

There are (2N) numbers that will be placed on a circle. Diego chooses one contiguous block of exactly (N) positions, and Googles receives the other (N) positions. Since the two blocks cover the entire circle, if Diego gets a sum of (X), Googles gets the total sum minus (X).

Practice › Codeforces Solutions › Semana i 2019 ›

CF 102409G - Ironical Solution 2

The encrypted message is not an arbitrary collection of numbers. There are exactly (2^N) values, one for every subset of the original (N) character codes.

Practice › Codeforces Solutions › Semana i 2019 ›

CF 102409F - Ironical Solution 1

We are given a word whose characters are already sorted by their ASCII values. We replace every character by its ASCII code, obtaining an array of (N) positive integers.

Practice › Codeforces Solutions › Semana i 2019 ›

CF 102409A - Easy Math

For each test case, we have three positive integers (A), (B), and (C). We first add (A) and (B), then divide that sum by (C). The required output is the decimal representation of the result with exactly 50 digits after the decimal point.

Practice › Codeforces Solutions › Semana i 2019 ›

CF 102409B - Xor Sums

For each test case, we are given an integer (N), and we need to compute the bitwise XOR of every integer from (1) through (N): [ 1 oplus 2 oplus 3 oplus cdots oplus N. ] The order does not matter because XOR is associative and commutative.

Practice › Codeforces Solutions › Semana i 2019 ›

CF 102409C - Xor in Tree

We have a weighted tree with (N) vertices. Each edge stores an integer, and for any two vertices we define their path value as the XOR of all edge weights on the unique path connecting them. The task is to add these path values over every unordered pair of distinct vertices.