# Common Child in Algorithm | HackerRank Programming Solutions | HackerRank Problem Solving Solutions in Java [💯Correct]

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#### Introduction To Algorithm

The word Algorithm means “a process or set of rules to be followed in calculations or other problem-solving operations”. Therefore Algorithm refers to a set of rules/instructions that step-by-step define how a work is to be executed upon in order to get the expected results.

### Advantages of Algorithms:

• It is easy to understand.
• Algorithm is a step-wise representation of a solution to a given problem.
• In Algorithm the problem is broken down into smaller pieces or steps hence, it is easier for the programmer to convert it into an actual program.

Link for the ProblemCommon Child – Hacker Rank Solution

`Common Child – Hacker Rank Solution`

### Problem:

A string is said to be a child of a another string if it can be formed by deleting 0 or more characters from the other string. Letters cannot be rearranged. Given two strings of equal length, what’s the longest string that can be constructed such that it is a child of both?

Example

These strings have two children with maximum length 3, `ABC` and `ABD`. They can be formed by eliminating either the `D` or `C` from both strings. Return .

Function Description

Complete the commonChild function in the editor below.

commonChild has the following parameter(s):

• string s1: a string
• string s2: another string

Returns

• int: the length of the longest string which is a common child of the input strings

Input Format

There are two lines, each with a string,  and .

Constraints

•  where  means “the length of “
• All characters are upper case in the range ascii[A-Z].

Sample Input

```HARRY
SALLY
```

Sample Output

``` 2
```

Explanation

The longest string that can be formed by deleting zero or more characters from  and  is , whose length is 2.

Sample Input 1

```AA
BB
```

Sample Output 1

```0
```

Explanation 1

and  have no characters in common and hence the output is 0.

Sample Input 2

```SHINCHAN
NOHARAAA
```

Sample Output 2

```3
```

Explanation 2

The longest string that can be formed between  and  while maintaining the order is .

Sample Input 3

```ABCDEF
FBDAMN
```

Sample Output 3

```2
```

Explanation 3
is the longest child of the given strings.

`Common Child – Hacker Rank Solution`
```import java.util.Scanner;

public class CommonChild {

static int commonChild(String s1, String s2) {
return LCSM4(s1.toCharArray(), s2.toCharArray(), s1.length(), s2.length());

}

public static int LCSM4(char[] X, char[] Y, int m, int n) {
int memo[] = new int[n + 1];

for (int i = 1; i <= m; i++) {
int prev = 0;
for (int j = 1; j <= n; j++) {
int temp = memo[j];
if (X[i - 1] == Y[j - 1]) {
memo[j] = prev + 1;
} else {
memo[j] = Math.max(memo[j], memo[j - 1]);
}
prev = temp;
}

}
return memo[n];
}

public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
String s1 = sc.next();
String s2 = sc.next();
int result = commonChild(s1, s2);
System.out.println(result);
sc.close();
}

}``` #### Ads Blocker Detected!!!

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