# Java: Reads an integer n and find the number of combinations of a,b,c and d will be equal to n

## Java Basic: Exercise-216 with Solution

Write a Java program which reads an integer n and finds the number of combinations of a,b,c and d (0 ≤ a,b,c,d ≤ 9) where (a + b + c + d) equals n.

Input:

n (1 ≤ n ≤ 50).

Sample Solution:

Java Code:

``````import java.util.Scanner;

public class Main {
public static void main(String[] args) {
// Prompting the user to input the number (n)
System.out.println("Input the number(n):");

// Creating a Scanner object for user input
Scanner s = new Scanner(System.in);

// Reading the input number (n) from the user
int c = s.nextInt();

// Calling the check method to find the number of combinations
int ans = check(c);

// Displaying the number of combinations of a, b, c, and d
System.out.println("Number of combinations of a, b, c, and d :");
System.out.println(ans);
}

// Method to check the number of combinations
static int check(int c) {
// Initializing a counter for combinations
int ctr = 0;

// Nested loops to iterate through all possible combinations of a, b, c, and d
for (int i = 0; i < 10; i++) {
for (int j = 0; j < 10; j++) {
for (int k = 0; k < 10; k++) {
for (int l = 0; l < 10; l++) {
// Checking if the sum of a, b, c, and d equals the input number (n)
if (i + j + k + l == c) {
// Incrementing the counter for valid combinations
ctr++;
}
}
}
}
}

// Returning the total number of combinations
return ctr;
}
}
```
```

Sample Output:

```Input the number(n):
5
Number of combinations of a, b, c and d :
56
```

Flowchart:

Java Code Editor: