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tamnd's digital brain — notes, problems, research
41230 notes
A set $V subseteq {0,1}^n$ closed under $oplus$ (bitwise addition modulo $2$) is a vector space over $mathbb{F}2$ under the usual operations. The zero vector $0^n$ belongs to $V$, and closure under $oplus$ implies closure under finite XOR-sums.
The problem statement you provided only contains the label “F” without any description of the input, output, or rules.
Let $q$ be a primitive $m$th root of unity and let N = n_1 + \cdots + n_t.
Let $q$ be a primitive $m$th root of unity and let N = n_1 + \cdots + n_t.
Let $C=(c1,c2,c3,c4,c5)$ be an ordered 5-card selection of distinct cards from a standard $52$-card deck, and let $k in {1,2,3,4,5}$ designate the starter card. The object counted is the pair $(C,k)$. Let $Sigma(C,k)$ denote the cribbage score defined by rules (i)-(v).
The statement as provided is not sufficient to reconstruct the problem. Right now the input and output sections are empty and the only identifier is “Harmony Coloring”, which is not enough to reliably infer the rules, constraints, or required output behavior.
Let $q$ be a primitive $m$th root of unity.
Let $q$ be a primitive $m$th root of unity, so $q^m=1$ and $1+q+\cdots+q^{m-1}=0$.
The problem is about simulating or evaluating a confrontation scenario over a linear structure of positions, where each position contains a value representing some strength, cost, or contribution to the battle outcome.
We are given a collection of matryoshka dolls, each with a numeric size. A doll can be placed inside another doll only if its size is strictly smaller. Each doll can contain at most one other doll directly, so the structure we build is a chain rather than a branching structure.
Let $\beta_0,\ldots,\beta_{M-1}$ be a revolving-door listing of all $(s,t)$-combinations of ${0,1,\ldots,s+t-1}$, where $M=\binom{s+t}{t}$, and consecutive terms differ by a single adjacent exchange i...
Represent each domino ${i,j}$, $0 le i le j le 6$, as an undirected edge between vertices $i$ and $j$ in a multigraph $G$ on vertex set ${0,1,dots,6}$, with one loop at each vertex $i$ corresponding to ${i,i}$.
Let $\beta_0,\ldots,\beta_{M-1}$ be a revolving-door listing of all $(s,t)$-combinations of ${0,1,\ldots,s+t-1}$, where $M=\binom{s+t}{t}$, and consecutive terms differ by a single adjacent exchange i...
We are given a snapshot from two different birthdays of two brothers who always celebrate on the same day of the year, which means their ages always increase synchronously by exactly one each year. At some past birthday, Vitya was n years old and his brother was m years old.
We are given a binary string $t$, and we are allowed to compare it against a special infinite family of binary strings $sm$. Each $sm$ is fixed: it starts with 0 and alternates every position, so it looks like 0101… up to length $m$.
Algorithm E generates all permutations by a sequence of adjacent interchanges and returns to the starting permutation, as indicated by its structure involving steps $E2$ and $E5$, and by the cyclic in...
Step E5 performs the single operation a_{j-c_j+s} \leftrightarrow a_{j-q+s}.
The flaw in the previous solution is that it never connects the modified step $E5'$ to the _actual control structure_ of Algorithm E.
We are given a patient who may suffer from exactly one disease among $k$ candidates. There are $n$ available medical tests. Each test checks a specific disease $di$, takes $ti$ minutes, and consumes $bi$ milliliters of blood.
We are given a word that belongs to exactly one of two alien alphabets. One alphabet uses only the letters A and B, while the other uses only the digits 0 and 1.
Define \gamma_m=\beta_m\alpha_m.
We are given a patient who may suffer from exactly one disease among $k$ candidates. There are $n$ available medical tests. Each test checks a specific disease $di$, takes $ti$ minutes, and consumes $bi$ milliliters of blood.
We are given a permutation of the numbers from 1 to n, and the goal is to transform it into the identity permutation where every position i contains value i. Two operations are available. One operation lets us swap any two elements at a fixed cost a.
We are asked to process a collection of weighted geometric updates and then answer queries about how much total weight lies inside axis-aligned prefix rectangles of the form $[1, x] times [1, y]$.
We are given a tree rooted at vertex 1, where each vertex has an integer weight. Along with the tree, we are given two parameters, a lower bound L and an upper bound R, and a target number K.
Let the prefix operation in step C3 be denoted by a transformation on ordered $k$-tuples.
Let Algorithm H act on a Sims table ${S_k}_{1 \le k \le n}$ as in Section 7.
Let the Sims table (36) be the standard Sims table for the symmetric group on $n$ symbols, in which the basic generators are the adjacent transpositions acting on positions, so that each entry $\sigma...
The statement is **false in general**.
We are given an undirected graph and we want to evaluate, for each vertex, how “critical” it is under a slightly non-standard notion of connectivity.
The problem deals with two collections of points, one set we can think of as set U and another as set V. Each point is not just a single number but a pair of coordinates, written as (ux, uy) for elements in U and (vx, vy) for elements in V.
We are given an array that is guaranteed to start in non-increasing order, so values never go up as we move to the right. On this array we must support two kinds of operations. The first operation modifies a single interior position.
We restart the argument from the actual structure of (13), tracking how each update clause transforms under the duality map, and we verify case by case that the transformed rules are exactly those of...
Consider an additive alphametic in base $10$ of the form \text{SEND} + \text{MORE} = \text{MONEY}, where distinct letters represent distinct digits in ${0,1,\dots,9}$ and leading letters $S$ and $M$ a...
Algorithm $X$ and Algorithm $L$ both enumerate all $n!$ permutations of $a_1 a_2 \dots a_n$.
I can’t reliably write a correct Codeforces-style editorial for “103604L - Uranium” without the actual problem statement.
Let $C_t(n)$ denote the lexicographically ordered sequence of all $t$-combinations $c_t \ldots c_1$ of ${0,1,\ldots,n-1}$ in the sense of Algorithm L.
I’m missing the actual problem statement for Codeforces 103604I - River, so I can’t reliably reconstruct the intended solution or write a correct editorial.
Let endo-order be the order on fixed-length binary strings induced by lexicographic order on their numeric representations, as used throughout Section 7.
We are given a tree of houses where house 1 is a special node acting as a permanent shelter. Every house initially contains some number of people. The roads between houses are bidirectional, and initially all roads are usable. We process two types of updates.
I can’t reliably write a correct editorial for this without the actual problem statement. “Codeforces 103604E - Intervals” isn’t a standard public statement I can reconstruct from the title alone, and guessing would very likely produce a completely wrong solution and…
Let endo-order be the order on fixed-length binary strings induced by lexicographic order on their numeric representations, as used throughout Section 7.
I can’t produce a correct Codeforces-style editorial yet because the problem statement for “103604D - Rainy Garden” is not actually included in your prompt, and it is not uniquely recoverable from the contest ID alone.
I don’t have the actual statement of Codeforces 103604H - Magic Powers in your prompt, so I can’t reliably reconstruct the problem, constraints, or the intended solution path.
Let an $(s,t)$-combination be represented by a binary string $a_{n-1}\dots a_0$ with $n=s+t$ and $\sum a_i=t$, as in Section 7.
I’m missing the actual problem statement for Codeforces 103604G - Parenthesis, and I can’t reliably reconstruct it from the ID alone.
I can’t safely write a correct editorial yet because the actual problem statement for Codeforces 103604F - Kube is not included in your prompt, and I don’t have reliable access to it from the information available here.
I can’t reliably write an editorial yet because the actual problem content for Codeforces 103604C - TimeToFarm is missing from your prompt (the statement, input/output definitions, and constraints are all blank).
I can’t write a correct editorial for this yet because the actual problem statement for Codeforces 103604A - CoinFlip is missing from your prompt.
I can’t write a correct editorial for this yet because the actual problem statement is missing. Right now I only see the title “103600K - Class Optimization”, but no description of the input, output, or task.
The problem statement for Codeforces 103600G - Resolution is not included in your prompt, so I don’t have enough information to write a correct editorial.
I don’t have the statement of Codeforces 103600I - Two Operations available in the prompt, and it’s essential for writing a correct editorial (especially since the structure, constraints, and even what the “two operations” are can completely change the solution).
I’m going to stop for a second here because the task cannot be completed correctly yet. The full problem statement for Codeforces 103600D (“Длинная территория”) is missing from your prompt, and the name alone is not sufficient to reliably reconstruct the…
I can’t write a correct editorial for this yet because the actual problem statement is missing. Right now I only know the title “Obstacle Course”, but there are no details about what the grid/graph/constraints are, what operations are allowed, or what needs to be computed.
Let $n = s + t$.
We are given a patient who may suffer from exactly one disease among $k$ candidates. There are $n$ available medical tests. Each test checks a specific disease $di$, takes $ti$ minutes, and consumes $bi$ milliliters of blood.
Let $n = s + t$.
The statement you pasted is corrupted, so the actual problem content (what “simplified crossing” means, what the inputs/outputs are) is missing. Without that, any editorial would be guessing, which would make the solution meaningless.
Let $n = s + t$.
Let $Sigman = {0,1,2}^n$. Two $n$-trits $x = (x1,dots,xn)$ and $y = (y1,dots,yn)$ are adjacent in an anti-Gray ternary code if and only if $xi neq yi$ for every $1 le i le n$.
Heap’s method (27) constructs permutations of $n$ objects by a recursive decomposition in which a size-$n$ problem is reduced to a size-$(n-1)$ problem, and each return from recursion is accompanied b...
We are interacting with a hidden integer $N$ that starts somewhere in the range $[1, 10^9]$. We cannot read it directly. Instead, we can apply four operations that modify the current value stored inside the judge. Two operations always succeed: adding 9 and multiplying by 9.
Working
Let $Sigman = {0,1,2}^n$. Two $n$-trits $x = (x1,dots,xn)$ and $y = (y1,dots,yn)$ are adjacent in an anti-Gray ternary code if and only if $xi neq yi$ for every $1 le i le n$.
We are given an array of numbers of length $n$. From this array, a square $n times n$ table is constructed. Each cell at row $j$ and column $i$ is filled with the value $min(ai, aj)$.
The problem statement for Codeforces 103590E - Double trios is missing from your message, so I don’t have the actual task definition, constraints, or examples needed to write a correct editorial.
I can’t write a correct editorial for this yet because the actual problem statement for Codeforces 103586B - “Журнал квестов” is missing from your prompt.
Let $T$ denote the total number of transpositions performed by Ord-Smith’s algorithm (26) in generating a full cycle of $n!$ permutations, and let $X$ denote the number of transpositions per permutati...
A Sims table used by Algorithms G or H encodes, for each level of a stabilizer chain for $S_n$, a full set of coset representatives for the successive point stabilizers.
Let the $4\times 4$ board be identified with coordinates $(r,c)$, where $0\le r,c\le 3$, and the given labeling is \begin{matrix} 0 & 1 & 2 & 3\\ 4 & 5 & 6 & 7\\ 8 & 9 & a & b\\
Working
A signed permutation of ${1,2,dots,n}$ is a sequence $(a1,dots,an)$ in which ${ The goal is to construct a Hamiltonian path in the graph whose vertices are signed permutations and whose edges correspond exactly to these two operations.
I can’t write a correct editorial for this yet because the actual problem statement is missing. Right now I don’t know what “Подземная лаборатория” is asking for, what the input describes, or what output is required.
I can't write a correct editorial for this problem because the prompt does not actually include the problem statement. The sections labeled "Problem Statement", "Input", and "Output" are empty.
I don’t have the actual statement of Codeforces 103585I - Baobab in your prompt, so I can’t reconstruct the problem or produce a correct editorial yet.
A signed permutation of ${1,2,dots,n}$ is a sequence $(a1,dots,an)$ in which ${ The goal is to construct a Hamiltonian path in the graph whose vertices are signed permutations and whose edges correspond exactly to these two operations.
I can't write a correct editorial for this problem because the actual problem statement is missing. The prompt only contains: - Problem: Codeforces 103585K - Ceiba Tree - Empty Problem Statement - Empty Input - Empty Output Without the statement, it is impossible to determine…
The reviewer’s objections are all correct: the previous response never produced a single fully consistent alphametic, and in part (b) the proposed assignment is structurally impossible.
Let the digits ${1,2,\dots,9}$ be arranged in some permutation, and let two cuts and a division sign be inserted to form an expression of the form $A + \frac{B}{C},$ where $A,B,C$ are positive integer...
We correct the proof by replacing all heuristic exclusions with a finite structural analysis of the digit constraints.
Connection interrupted. Waiting for the complete answer
The problem statement for Codeforces 103585E - Truffula Trouble is missing from your message, so I don’t have the actual task definition (inputs, outputs, or rules) needed to write a correct editorial.
We solve \frac{A}{10B+C}+\frac{D}{10E+F}+\frac{G}{10H+I}=1, \qquad \{A,\dots,I\}=\{1,\dots,9\}.
A multiplicative alphametic is interpreted as a system of constraints over a partial injection $\varphi$ from letters to decimal digits, extended to numbers in base $10$ in the usual way.
The problem statement for “Codeforces 103585G - Perfect Cacti: Part 1” is missing from your message, so I can’t reconstruct the actual graph structure, required output, or constraints reliably.
Let $n = s + t$ and let $C_{st}$ denote Chase’s sequence of all $(s,t)$-combinations of ${0,1,\dots,n-1}$ as described in Section 7.
Let $n=s+t$ and consider genlex listings of $(s,t)$-combinations in index-list form $c_t c_{t-1}\dots c_1$ as defined by Algorithm $L$ in Section 7.
An additive alphametic in the sense of Section 7.
Solution to TAOCP 7.2.1.2 Exercise 26.
Let $a_1,\dots,a_{10}$ be a permutation of $\{0,1,\dots,9\}$, with the constraint $a_i \neq 0$ for $i \in F$.
Solution to TAOCP 7.2.1.2 Exercise 24.
The previous solution failed because it implicitly treated an “alphametic identity” as a manipulable symbolic cancellation pattern, rather than a polynomial identity that must hold for all digit assig...
The previous solution fails because it tries to separate bases via carry behavior, but an alphametic solution is not defined in terms of carries.
The task is about simulating how a sticky liquid spreads through a sequence of containers arranged in a line. Each container has a fixed capacity, and when liquid is poured into one container, it fills up to its limit and any excess immediately flows into the next container…
The previous solution fails at the point where it imports specific base-10 digits.
We construct an explicit Hamiltonian path on the Cayley graph of the hyperoctahedral group $B_n$, whose vertices are signed permutations of $\{1,\dots,n\}$.
Let $\alpha$ be a string of length $n=s+t$ on the alphabet ${+,-,0}$ satisfying the conditions of Exercise 29, so that $\alpha$ contains exactly $s$ signs and $t$ zeros.
Let a string $\alpha$ consist of symbols in ${+, -, 0}$.
Introduce an additional array $a'_{1}\ldots a'_{n}$ alongside Algorithm P, where at all times $a'_{k}=j$ if and only if $a_{j}=k$.
Connection interrupted.