sgn function#8608

sgn function (Editorial)

Use the conditional statement to solve the problem.

Let's consider another solution. Write the condition as follows:

y = 1 \cdot (x > 0) + 0 \cdot (x == 0) + (- 1) \cdot (x < 0);

y = 1 \cdot (x > 0) + 0 \cdot (x == 0) + (-1) \cdot (x < 0);

y = (x > 0) - (x < 0);

y = (x > 0) - (x < 0);

For example, if

$x$ is positive, then $y = 1 - 0 = 1$ y = 1 - 0 = 1;
$x = 0$ x = 0, then $y = 0 - 0 = 0$ y = 0 - 0 = 0;
$x$ is negative, then $y = 0 - 1 = - 1$ y = 0 - 1 = -1;

Algorithm realization

Read the input value of $x$ .

scanf("%d", &x);

Compute the value of the sgn function.

if (x > 0)  y = 1; else
if (x == 0) y = 0; else
            y = -1;

Print the answer.

printf("%d\n", y);

Algorithm realization — without if

Read the input value of $x$ .

scanf("%d", &x);

Compute the value of the sgn function.

y = (x > 0) - (x < 0);

Print the answer.

printf("%d\n", y);

Java realization

import java.util.*;

public class Main
{
  public static void main(String[] args) 
  {
    Scanner con = new Scanner(System.in);
    int y, x = con.nextInt();

    if (x > 0)  y = 1; else
    if (x == 0) y = 0; else
      y = -1;

    System.out.println(y);
    con.close();
  }
}

Java

Python realization

Read the input value of $x$ .

x = int(input())

Compute the value of the sgn function.

if x > 0: y = 1
elif x == 0: y = 0
else: y = -1

Print the answer.

print(y)

Python realization — without if

Read the input value of $x$ .

x = int(input())

Compute the value of the sgn function.

y = (x > 0) - (x < 0)

Print the answer.

print(y)