How can I swap the values of two variables ?
This works, but I'd would prefer a one liner :
int a = 10, b = 30;
a = a + b;
b = a - b;
a = a - b;
Perhaps that's cheating but there's simply :
std::swap(a, b);
std::tie(x,y) = std::make_pair(y,x);
But std::swap(x,y) is much more readable and probably more efficient.
int main()
{
int x = 10, y = 10;
y = (x + y)-y;
}
Solved a little bit but not completely but solved if you use this code
int swap(int *x, int y){
*x = (*x + *y) - *x;
return 0;
}
int main()
{
int x = 10;
int y = 5;
y = (x + y) - y + swap(&x, &y);
cout << x << endl << y << endl;
}
Related
Heres the code:
int gcdExtended(int a, int b, int* x, int* y);
void modInverse(int A, int M)
{
int x, y;
int g = gcdExtended(A, M, &x, &y);
if (g != 1)
cout << "Inverse doesn't exist";
else {
int res = (x % M + M) % M;
cout << "Modular multiplicative inverse is " << res;
}
}
int gcdExtended(int a, int b, int* x, int* y)
{
// Base Case
if (a == 0) {
*x = 0, *y = 1;
return b;
}
// To store results of recursive call
int x1, y1;
int gcd = gcdExtended(b % a, a, &x1, &y1);
*x = y1 - (b / a) * x1;
*y = x1;
return gcd;
}
I'm not sure how to take in bigger numbers like 15001 (mod 5729413260) without getting overflow. Should I not use recursion? I tried long long but that didn't work, any suggestions?
You might change int to long long; if that's not sufficient, then boost::multiprecision might help.
Given two int I want to get all the common digits and print out them separated by spaces.
So for example, if int x=1234; int y=41567; then I want to print out: 1 4.
This is my code. It does not work properly. When I run it, it prints 0 1 2 3 4 5 then stops.
I don't want to use vector nor arrays.
void problema3() {
int x, y, kX=0, kY=0;
cout << "x="; cin >> x;
cout << "y="; cin >> y;
int cx = x;
int cy = y;
for (int i = 0; i < 10; i++) {
kX = 0;
kY = 0;
x = cx;
y = cx;
while (x != 0 || kX==0) {
if (x % 10 == i) kX=1;
x /= 10;
}
while (y != 0 || kY == 0) {
if (y % 10 == i) kY=1;
y /= 10;
}
if (kX == 1 && kY == 1) cout << i << ' ';
}
}
int main()
{
problema3();
return 0;
}
If you're allowed to use std::set then you can do what you want as follows:
#include <iostream>
#include <set>
void print(int x, int y)
{
int individual_number1 = 0, individual_number2 = 0;
std::set<int> myset;
int savey = y;//this will be used to reset y when the 2nd do while loop finishes
do
{
individual_number1 = x % 10;
do
{
individual_number2 = y % 10;
if(individual_number1 == individual_number2)
{
myset.insert(individual_number1);
break;
}
y = y / 10;
}while( y > 0);
y = savey;
x = x / 10;
} while (x > 0);
//print out the element of the set
for(int i: myset)
{
std::cout<<i<<" ";
}
}
int main()
{
int x = 1234, y = 41567;
print(x, y);
return 0;
}
The output of the above program is as follows:
1 4
which can be seen here.
Your main bug is when assigning copies of cy.
//...
for (int i = 0; i < 10; i++) {
//...
x = cx;
y = cx; // <-- BUG! should read y = cy;
But that's not the only bug in your program.
Your digit detection logic is wrong. In particular, zero is not handled correctly, and since you did not put that reusable code in a function, your program is way more complex than it needs.
Here's the corrected logic for digit detection.
// checks if base 10 representation of a positive integer contains a certain digit (0-9)
bool hasDigit(int x, int d)
{
do
{
if (x % 10 == d)
return true;
x /= 10;
} while (x != 0);
return false;
}
Your main loop then becomes:
// assuming int x, y as inputs.
// ...
for (int i = 0; i < 10; ++i)
{
if (hasDigit(x, i) && hasDigit(y, i))
std::cout << i << ' ';
}
Which leaves very little room for bugs.
You can play with the code here: https://godbolt.org/z/5c5brEcEq
This is the code. When I run it, nothing appears, just darkness. Blank.
I'm a beginner, and I don't really know too much about coding. Any help would be appreciated.
#include <iostream>
using namespace std;
int main()
float x;
float y;
float Wynik;
x = 1.4;
y = 5.8;
Wynik = (x * y + x + y) / (x-y);
return 0;
}
Because you aren't printing out anything in your console. To print your results, use std::cout << Wynik;. And also, you have an error in your main function, it's supposed to be like this:
int main() {
// Your code goes here
}
Also, using namespace std; is considered bad practice since it can lead to conflicts with your other libraries, but you'll read that in a book.
#include <iostream>
using namespace std;
int main() {
float x;
float y;
float Wynik;
x = 1.4;
y = 5.8;
Wynik = (x * y + x + y) / (x-y);
cout << Wynik << endl; // This will print your output
return 0;
}
#include <iostream>
int main()
{
const float x = 1.4;
const float y = 5.8;
std::cout << (x * y + x + y) / (x - y) << std::endl; // This will print your output
return 0;
}
For the code below why are the variables x,y,s pass-by-value while only z is pass-by-reference.
void foo(int* a, int* b, int& c, int d) {
*a = *a + 1;
b = b + 1;
c = c + 1;
d = d + 1;
}
int main() {
int x = 0, y = 5, z = 10, s = 20;
foo(&x, &y, z, s);
cout << x << “, ” << y << “, ” << z <<“, ” << s <<endl;
return 0;
}
in function foo() a,and b are pointers ie, they will take address of the variable and in function call addresses of x and y are passed. But c takes reference to the argument provided .
You can see C program examples here on geeksforgeeks
I'm trying to implement Karatsuba algorithm for multiplication. I'm kinda follow the pseudocode in this wiki page. But I'm always getting this error:
terminated by signal SIGSEGV (Address boundary error)
When I replaced the lines that cause the recursion to happen with something else:
z0 = multiply(a, c);
z1 = multiply(b, d);
z2 = multiply(a+b, c+d);
the error disappeared.
Here's my code:
#include <iostream>
#include <math.h>
long int multiply(int x, int y);
int get_length(int val);
int main()
{
int x = 0, y = 0;
long int result = 0;
std::cout << "Enter x: ";
std::cin >> x;
std::cout << "Enter y: ";
std::cin >> y;
result = multiply(x, y);
std::cout << "Result: " << result << std::endl;
return 0;
}
long int multiply(int x, int y)
{
if(x < 10 || y < 10) {
return x * y;
}
int x_len = get_length(x);
int y_len = get_length(y);
long int z0 = 0 , z1 = 0, z2 = 0;
int a = 0, b = 0, c = 0, d = 0;
a = x / pow(10, x_len);
b = x - (a * pow(10, x_len));
c = y / pow(10, y_len);
d = y - (c * pow(10, y_len));
z0 = multiply(a, c);
z1 = multiply(b, d);
z2 = multiply(a+b, c+d);
return (pow(10, x_len) * z0) + (pow(10, x_len/2) * (z2 - z1 - z0)) + z1;
}
int get_length(int val)
{
int count = 0;
while(val > 0) {
count++;
val /= 10;
}
return count;
}
I found the problem cause.
It was because of these lines:
a = x / pow(10, x_len);
b = x - (a * pow(10, x_len));
c = y / pow(10, y_len);
d = y - (c * pow(10, y_len));
It should be x_len / 2 instead of x_len and the same with y_len. Since it causes the recursion to be infinite.
You are using the pow function to do integer powers. It is not an integer function. Code your own pow function that's suitable for your application. For example:
int pow(int v, int q)
{
int ret = 1;
while (q > 1)
{
ret*=v;
q--;
}
return ret;
}
Make sure to put an int pow(int, int); at the top.