Recursion in Java

Recursion in Java

In Java, Recursion is a process in which a function calls itself directly or indirectly is called recursion and the corresponding function is called a recursive function.

case Condition in Recursion

In the recursive program, the solution to the base case is provided and the solution to the bigger problem is expressed in terms of smaller problems.

int fact(int n)
{
    if (n < = 1) // base case
        return 1;
    else    
        return n*fact(n-1);    
}
int fact(int n)
{
    if (n < = 1) // base case
        return 1;
    else    
        return n*fact(n-1);    
}
int fact(int n)
{
    if (n < = 1) // base case
        return 1;
    else    
        return n*fact(n-1);    
}

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In the above example, the base case for n < = 1 is defined and the larger value of a number can be solved by converting it to a smaller one till the base case is reached.

Working of Recursion

The idea is to represent a problem in terms of one or more smaller sub-problems and add base conditions that stop the recursion. For example, we compute factorial n if we know the factorial of (n-1). The base case for factorial would be n = 0. We return 1 when n = 0

// Factorial using recursion
class GFG {
    // recursive method
    int fact(int n)
    {
        int result;
        if (n == 1)
            return 1;
        result = fact(n - 1) * n;//ex-4 mean 4*3*2*1
        return result;//ex-4 mean ans--24
    }
}
// Driver Class
class Recursion {
    // Main function
    public static void main(String[] args)
    {
        GFG f = new GFG();
        System.out.println("Factorial of 3 is "
                           + f.fact(3));
        System.out.println("Factorial of 4 is "
                           + f.fact(4));
        System.out.println("Factorial of 5 is "
                           + f.fact(5));
    }
}
// Factorial using recursion
class GFG {

    // recursive method
    int fact(int n)
    {
        int result;

        if (n == 1)
            return 1;
        result = fact(n - 1) * n;//ex-4 mean 4*3*2*1
        return result;//ex-4 mean ans--24
    }
}

// Driver Class
class Recursion {

    // Main function
    public static void main(String[] args)
    {
        GFG f = new GFG();

        System.out.println("Factorial of 3 is "
                           + f.fact(3));
        System.out.println("Factorial of 4 is "
                           + f.fact(4));
        System.out.println("Factorial of 5 is "
                           + f.fact(5));
    }
}
// Factorial using recursion
class GFG {

    // recursive method
    int fact(int n)
    {
        int result;

        if (n == 1)
            return 1;
        result = fact(n - 1) * n;//ex-4 mean 4*3*2*1
        return result;//ex-4 mean ans--24
    }
}

// Driver Class
class Recursion {

    // Main function
    public static void main(String[] args)
    {
        GFG f = new GFG();

        System.out.println("Factorial of 3 is "
                           + f.fact(3));
        System.out.println("Factorial of 4 is "
                           + f.fact(4));
        System.out.println("Factorial of 5 is "
                           + f.fact(5));
    }
}

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Output

Factorial of 3 is 6
Factorial of 4 is 24
Factorial of 5 is 120

Reference:https://www.geeksforgeeks.org/recursion-in-java/

原文链接：Recursion in Java