수다닷컴

다항식 덧셈 뺄셈 곱셈인데.. 자꾸 곱셈에서 에러가 납니다..

뭐가 잘못 됐는지 좀 가르쳐 주세요...

class Node {
int coef;
int exp;
Node link;

public Node(int x, int y) {
coef = y;
exp = x;
link = null;
}
}

public class Poly {
private Node head;
private Node last;

public Poly() {
head = null;
last = null;
}

public void appendTerm(int x, int y) {
Node newNode = new Node(x, y);

if (head == null) {
head = newNode;
last = newNode;
}
else {
last.link = newNode;
last = newNode;
}
}

public Poly polyAdd(Poly a) {
Node p = this.head;
Node q = a.head;

Poly res = new Poly();

while (p != null && q != null) {
if (p.exp == q.exp) {
if (p.coef + q.coef == 0) {
p = p.link;
q = q.link;
}
else {
res.appendTerm(p.exp, p.coef + q.coef);
p = p.link;
q = q.link;
}
}

else if (p.exp q.exp) {
res.appendTerm(q.exp, q.coef);
q = q.link;
}
else {
res.appendTerm(p.exp, p.coef);
p = p.link;
}
}

while (p != null)
{
res.appendTerm(p.exp, p.coef);
p = p.link;
}

while (q != null)
{
res.appendTerm(q.exp, q.coef);
q = q.link;
}
return res;
}

public Poly polyDiff(Poly a) {

Node p = this.head;
Node q = a.head;
Poly res = new Poly();

while (p != null && q != null) {
if (p.exp == q.exp) {
if (p.coef + q.coef == 0) {
p = p.link;
q = q.link;
}
else {
res.appendTerm(p.exp, p.coef - q.coef);
p = p.link;
q = q.link;
}

}
else if (p.exp q.exp) {
res.appendTerm(q.exp, -q.coef);
q = q.link;
}
else {
res.appendTerm(p.exp, p.coef);
p = p.link;
}
}

while (p != null) {
res.appendTerm(p.exp, p.coef);
p = p.link;
}
while (q != null)
{
res.appendTerm(q.exp, q.coef);
q = q.link;
}
return res;
}

public Poly polyMul(Poly a) {
Node p = this.head;
Node q = a.head;
Node x;

Poly res = new Poly();
Node temp = res.head;

while (p != null) {
while (q != null) {
x.exp = p.exp + q.exp;
if (temp == null) {
while (q != null) {
res.appendTerm(p.exp + q.exp, p.coef * q.coef);
q = q.link;
}
}

else {
while (temp !=null) {
if (temp == x.exp) {
res = temp;
&; res.coef += p.coef * q.coef;
temp = temp.link;
}
else if (temp x.exp) {
temp = temp.link;
}
else {
res = temp;
res.appendTerm(p.exp + q.exp, p.coef * q.coef);
temp = temp.link;
}

}
temp = res.head;
}
q = q.link;
}
q = a.head;
p = p.link;
}
return res;
}

public void print() {
Node temp = head;
while (temp != null) {
if (!temp.equals(head)) {
if (temp.coef = 0)
System.out.print( + );
else
System.out.print( - );

}
if (head == temp)
System.out.print(temp.coef + x^ + temp.exp);

else if (temp.exp == 0) {
System.out.print(temp.coef);
}
else {
if (temp.coef = 0)
System.out.print(temp.coef + x^ + temp.exp);
else
System.out.print(-temp.coef + x^ + temp.exp);
}
temp = temp.link;
}
System.out.println();
}

public static void main(String args[])
{
Poly p1 = new Poly();

p1.appendTerm(3, 5);
p1.appendTerm(2, 1);
p1.appendTerm(0, 7);

System.out.print(A = );
p1.print();

Poly p2 = new Poly();

p2.appendTerm(4, 2);
p2.appendTerm(2, -8);
p2.appendTerm(1, 4);

System.out.print(B = );
p2.print();

Poly p3 = p1.polyAdd(p2);
System.out.print(A + B = );
p3.print();
Poly p4 = p1.polyDiff(p2);
System.out.print(A - B = );
p4.print();
Poly p5 = p1.polyMul(p2);
System.out.print(A * B = );
p5.print();
}
}

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