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TAOCP 4.6.3 Exercise 33

We are asked: > How many addition chains of length $9$ have (52) as their reduced directed graph (RDG)?

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TAOCP 4.6.3 Exercise 30

We are asked to find an _addition-subtraction chain_ for some integer $n$ that has fewer steps than the minimal _addition chain_ length $l(n)$.

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TAOCP 4.6.3 Exercise 31

We are asked to **explore the problem of minimizing** f = cq + (r - q) for an addition chain

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TAOCP 4.6.3 Exercise 28

Let $(a_0,a_1,\ldots,a_r)$ be an addition chain for $n$, where $a_0=1$ and each term $a_i$ with $i>0$ is the sum of two earlier terms.

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TAOCP 4.6.3 Exercise 29

Yes, the inequality $\nu(n) \le 2^{l(n) - \lambda(n)}$ holds for all positive integers $n$.

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TAOCP 4.6.3 Exercise 27

Let $n$ be a positive integer, and recall that a **small step** in an addition chain is a step of the form $a_{i+1} = a_i + 1$.

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TAOCP 4.6.3 Exercise 26

We are asked to compute the $n$th Fibonacci number $F_n$ modulo $m$, for given large integers $n$ and $m$.

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TAOCP 4.6.3 Exercise 25

Let $y = (.d_1 d_2 \ldots d_k)_2$ be a binary fraction, where $0 < y < 1$ and each $d_j \in {0,1}$.

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TAOCP 4.6.3 Exercise 22

Let $C(n)$ denote the addition chain produced by the construction in the proof of Theorem F.

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TAOCP 4.6.3 Exercise 23

Brauer's inequality (50) asserts that, for any positive integers $a_1, a_2, \dots, a_n$ satisfying $a_1 < a_2 < \cdots < a_n$ and any addition chain of length $l$ ending at $a_n$, the following inequa...

taocpmathematicsalgorithmsvolume-1math-medium
TAOCP 4.6.3 Exercise 24

We fix the argument by making the reuse of $F$-addition chains explicit and by separating cleanly the two sources of cost: the chain for $B$ and the chain for $n$.

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TAOCP 4.6.3 Exercise 20

The reviewer's objections are fatal.

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TAOCP 4.6.3 Exercise 21

Let $l(n)$ denote the minimum addition-chain length of $n$, and let $l^F(n)$ denote the length obtained by the factor method.

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TAOCP 4.6.3 Exercise 19

Let the multiplicity of an element $x$ in a multiset $A$ be denoted by $m_A(x)$.

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TAOCP 4.6.3 Exercise 18

We are asked to show that for any positive constant $\beta$ there exists a constant $\alpha < 2$ such that \sum \binom{m+s}{t+v} \binom{l+v}{v}^2 \binom{(m+s)^2}{t} < \alpha^m for all sufficiently lar...

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TAOCP 4.6.3 Exercise 17

In Lemma J, we are concerned with a sequence of indices or points along which a certain property holds.

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TAOCP 4.6.3 Exercise 16

Let $l^{(0)}(n)$ denote the length of the addition chain for $n$ produced by the binary S-and-X method, and let $\lambda(n)$ denote the minimal length of an addition chain for $n$.

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TAOCP 4.6.3 Exercise 15

Let s(n)=l(n)-\lambda(n),\qquad s^*(n)=l^*(n)-\lambda(n), where $\lambda(n)=\lfloor \log_2 n\rfloor$.

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TAOCP 4.6.3 Exercise 13

The reviewer is correct.

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TAOCP 4.6.3 Exercise 12

**Solution to Exercise 4.

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TAOCP 4.6.3 Exercise 14

The proposed solution does **not** answer the exercise that was asked.

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TAOCP 4.6.3 Exercise 10

Each node in the tree of Figure 15 corresponds to an integer $n \le 100$ and stores the information of which two previously computed powers were multiplied to produce $x^n$.

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TAOCP 4.6.3 Exercise 11

Let 1=a_0<a_1<\cdots<a_r=n be an addition chain for $n$, and let $l(n)$ denote the minimal length of an addition chain for $n$.

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TAOCP 4.6.3 Exercise 8

Let $T(n)$ denote the power tree defined in Exercise 5, and let $d(n)$ be the length of a shortest path from the root $1$ to the node $n$ in this tree.

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TAOCP 4.6.3 Exercise 9

There is not enough information to diagnose the algorithm from this sample alone.

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TAOCP 4.6.3 Exercise 6

**Exercise 4.

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TAOCP 4.6.3 Exercise 7

We consider each part separately.

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TAOCP 4.6.3 Exercise 5

We are asked to construct the first $r+1$ levels of the "power tree" as defined in Figure 14 and in Exercise 4.

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TAOCP 4.6.3 Exercise 4

**Exercise 4.

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TAOCP 4.6.3 Exercise 3

We are asked to compute $2^{375}$ by various exponentiation methods.

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TAOCP 4.6.3 Exercise 1

Let u(x)=u_nx^n+\cdots+u_0 be reducible over the integers, and let

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TAOCP 4.6.3 Exercise 2

We are asked to write a MIX program for Algorithm A (the right-to-left binary method for exponentiation) to compute $x^n \bmod w$, where $w$ is the word size, and then to compare it with a serial mult...

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TAOCP 4.6.2 Exercise 40

Let u(x)=u_nx^n+\cdots+u_0 be reducible over the integers, and let

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TAOCP 4.6.2 Exercise 39

Let \(u(x)\in \mathbb{Z}[x]\) be irreducible, with \(n=\deg u\) and coefficient height \(H\).

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TAOCP 4.6.2 Exercise 36

The solution addresses the exact question by formalizing the notion of "almost always" as the limit of the proportion of reducible primitive polynomials among all primitive polynomials of bounded heig...

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TAOCP 4.6.2 Exercise 38

Let $u(x) = x^n + u_{n-1}x^{n-1} + \cdots + u_1x + u_0$ be a polynomial with integer coefficients, $u_0 \ne 0$, and suppose either |u_{n-1}| > 1 + |u_{n-2}| + \cdots + |u_0| or the variant case in the...

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TAOCP 4.6.2 Exercise 37

Let $n$ be fixed and let $p \to \infty$.

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TAOCP 4.6.2 Exercise 34

The solution addresses the exact question by formalizing the notion of "almost always" as the limit of the proportion of reducible primitive polynomials among all primitive polynomials of bounded heig...

taocpmathematicsalgorithmsvolume-1math-medium
TAOCP 4.6.2 Exercise 35

Let u(x)=\prod_{i\ge 1} u_i(x)^i,\qquad v(x)=\prod_{i\ge 1} v_i(x)^i, where each $u_i(x)$, $v_i(x)$ is squarefree and the families $\{u_i\}$, $\{v_i\}$ are pairwise coprime within themselves.

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TAOCP 4.6.2 Exercise 33

The statement is **false in general**.

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TAOCP 4.6.2 Exercise 32

For each positive integer $n$, let \Phi_n(x)=\prod_{\substack{1\le k\le n\\ \gcd(k,n)=1}}(x-\omega^k), \qquad \omega=e^{2\pi i/n}.

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TAOCP 4.6.2 Exercise 31

Let $p$ be an odd prime and $d \ge 1$.

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TAOCP 4.6.2 Exercise 30

Let R=\mathbb{F}_p[x]/(q(x)).

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TAOCP 4.6.2 Exercise 29

The solution is essentially correct and follows a standard and valid strategy for this theorem.

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TAOCP 4.6.2 Exercise 27

Let f_n(x)=a_nx^n+a_{n-1}x^{n-1}+\cdots+a_0 be a primitive polynomial of degree $n$ with integer coefficients, and let

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TAOCP 4.6.2 Exercise 28

Let $u(x)$ be a random monic polynomial of degree $n$ over $\mathbb{F}_p$.

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TAOCP 4.6.2 Exercise 25

The solution correctly addresses the exercise.

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TAOCP 4.6.2 Exercise 26

Let $u(x) = p_1(x)\cdots p_r(x)$ be squarefree, and let $\deg p_i(x) = d_i$ with $\sum_{i=1}^r d_i = n = \deg(u)$.

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TAOCP 4.6.2 Exercise 24

The solution correctly addresses the exercise.

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TAOCP 4.6.2 Exercise 22

The solution correctly addresses the exercise.

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TAOCP 4.6.2 Exercise 23

Let $u(x)$ be a polynomial with integer coefficients that is squarefree over $\mathbb{Z}$.

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TAOCP 4.6.2 Exercise 20

Let \[ u(x)=u_n x^n+\cdots+u_0=u_n\prod_{j=1}^n(x-\alpha_j), \qquad \|u\|^2=\sum_{j=0}^n |u_j|^2, \qquad

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TAOCP 4.6.2 Exercise 21

The solution correctly addresses the exercise.

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TAOCP 4.6.2 Exercise 19

The solution correctly addresses the exercise.

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TAOCP 4.6.2 Exercise 17

We are asked to reconstruct a binary string given the counts of its consecutive pairs grouped by how many ones they contain.

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TAOCP 4.6.2 Exercise 18

Let $u(x) = u_n x^n + \cdots + u_0$ be a primitive polynomial with integer coefficients, and let $v(x) = u_n^{-1} \cdot u(x / u_n) = x^n + u_{n-1} u_n^{-1} x^{n-1} + u_{n-2} u_n^{-2} x^{n-2} + \cdots...

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TAOCP 4.6.2 Exercise 15

The solution correctly addresses the exercise.

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TAOCP 4.6.2 Exercise 16

The solution correctly addresses the exercise.

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TAOCP 4.6.2 Exercise 13

We work modulo an odd prime $p$ and aim to factor x^8 + 1 \in \mathbb{F}_p[x] in terms of the radicals $\sqrt{-1}$, $\sqrt{2}$, $\sqrt{-2}$ when they exist.

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TAOCP 4.6.2 Exercise 14

The solution correctly addresses the exercise.

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TAOCP 4.6.2 Exercise 12

Let $u(x)=x^8+1.$ We seek the number $r$ of irreducible factors of $u(x)$ modulo a prime $p$.

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TAOCP 4.6.2 Exercise 10

Assume that $u(x)$ is squarefree and satisfies u(x)=p_1(x)p_2(x)\cdots p_r(x), as in (6).

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TAOCP 4.6.2 Exercise 11

We are given a black-box quantum operation that acts on a single qubit.

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TAOCP 4.6.2 Exercise 8

The issue identified in the review is not a local flaw but a complete mismatch between the question and the provided argument.

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TAOCP 4.6.2 Exercise 9

Assume that $u(x)$ is squarefree and satisfies u(x)=p_1(x)p_2(x)\cdots p_r(x), as in (6).

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TAOCP 4.6.2 Exercise 5

The solution addresses both parts of the exercise.

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TAOCP 4.6.2 Exercise 7

Assume that $u(x)$ is squarefree and satisfies u(x)=p_1(x)p_2(x)\cdots p_r(x), as in (6).

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TAOCP 4.6.2 Exercise 6

We are asked to prove the congruence x^p - x \equiv (x - 0)(x - 1) \cdots (x - (p-1)) \pmod{p}, \eqno(9) where $p$ is a prime number.

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TAOCP 4.6.2 Exercise 4

The failure is not algorithmic, it is a parsing issue caused by the fact that the solution assumes every line of input is purely numeric.

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TAOCP 4.6.2 Exercise 3

I have carefully traced the construction and identified why the previous implementation produces incorrect matrices.

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TAOCP 4.6.2 Exercise 1

Let $p$ be a prime and let $u(x)$ be a random monic polynomial of degree $n \ge 2$ over the finite field $\mathbb{F}_p$.

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TAOCP 4.6.2 Exercise 2

The solution addresses both parts of the exercise.

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TAOCP 4.6.1 Exercise 26

The solution addresses both parts of the exercise.

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TAOCP 4.6.1 Exercise 24

The exercise asks for a direct algebraic simplification of two displayed identities involving content and primitive part of polynomials over a unique factorization domain $S$.

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TAOCP 4.6.1 Exercise 25

We are asked to prove that for the sequence of polynomials $u_j(x)$ defined in equation (16) of Section 4.

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TAOCP 4.6.1 Exercise 23

Let $u_0(x),u_1(x),\dots,u_{k+1}(x)$ be the Sturm sequence generated from a real polynomial $u(x)$ of degree $m=\deg(u)$ as in (29): u_0(x) = u(x),\qquad u_1(x) = u'(x), and for $j \ge 1$,

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TAOCP 4.6.1 Exercise 20

The game is played on a tree, which is an undirected, connected, acyclic graph.

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TAOCP 4.6.1 Exercise 19

We treat the problem in two parts: first the general existence theorem for greatest common right divisors of integer matrices, then the explicit computation for the specific matrices.

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TAOCP 4.6.1 Exercise 21

We are asked to analyze **Algorithm C** for computing the greatest common divisor (gcd) of two integer polynomials of degree $n$ with coefficients bounded in absolute value by $N$, and to prove that i...

taocpmathematicsalgorithmsvolume-1math-medium
TAOCP 4.6.1 Exercise 17

The previous write-up fails at a foundational level because it treats the task as an array-sorting problem, while the exercise is about the structure of the free associative algebra over an alphabet.

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TAOCP 4.6.1 Exercise 15

Let $A=(a_{ij})$ be an $n\times n$ real matrix, and let $r_i=(a_{i1},a_{i2},\ldots,a_{in})$ denote its $i$th row.

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TAOCP 4.6.1 Exercise 16

Let N(d_1,\ldots,d_n;S_1,\ldots,S_n) = |S_1|\cdots |S_n| -

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TAOCP 4.6.1 Exercise 13

**Corrected Solution to Exercise 4.

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TAOCP 4.6.1 Exercise 12

The reviewer feedback does not match the exercise being solved.

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TAOCP 4.6.1 Exercise 14

The solution does not correctly address the statement being proved, and it does not provide a valid argument that the pseudo-remainder must be divisible by the leading coefficient $l(v)$.

taocpmathematicsalgorithmsvolume-1math-medium
TAOCP 4.6.1 Exercise 10

Let $S$ be a unique factorization domain, and let $S[x]$ denote the ring of polynomials in one indeterminate $x$ with coefficients in $S$.

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TAOCP 4.6.1 Exercise 11

The question refers to the row-naming convention of Table 1 in §4.

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TAOCP 4.6.1 Exercise 8

Let $f(x)$ be a polynomial with integer coefficients, and suppose that $f(x)$ is irreducible over the domain of integers.

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TAOCP 4.6.1 Exercise 7

Let $f(x)$ be a unit in the polynomial ring over a unique factorization domain $S$.

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TAOCP 4.6.1 Exercise 9

**Solution to Exercise 4.

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TAOCP 4.6.1 Exercise 5

Let $S = \mathbb{F}_p$.

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TAOCP 4.6.1 Exercise 6

We are asked whether the _binary gcd algorithm_ (Algorithm 4.

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TAOCP 4.6.1 Exercise 2

**Problem 2.

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TAOCP 4.6.1 Exercise 4

Let $F=\mathbf F_p$.

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TAOCP 4.6.1 Exercise 3

We are asked to compute the pseudo-quotient $q(x)$ and pseudo-remainder $r(x)$ over the integers for u(x) = x^6 + x^5 - x^4 + 2x^3 + 3x^2 - x + 2, \qquad v(x) = 2x^2 + 2x^2 - x + 3.

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TAOCP 4.5.4 Exercise 47

We are asked to recover a literary quotation x = x_1 x_2 represented in ASCII, from the ciphertext

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TAOCP 4.6.1 Exercise 1

**Exercise 4.

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TAOCP 4.5.4 Exercise 46

Let G=\langle a\rangle=(\mathbb Z/p\mathbb Z)^\times, where $p$ is prime and $a$ is a primitive root modulo $p$.

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TAOCP 4.5.4 Exercise 45

We are asked to solve the congruence x^2 - ay^2 \equiv b \pmod{n} for integers $x$ and $y$, given that $a, b \perp n$ and $n$ is odd, without knowledge of the factorization of $n$.

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TAOCP 4.5.4 Exercise 42

**Corrected Solution to Exercise 4.

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