Write two complete java programs to solve the following two problems. Make certain to document your code properly.

1)Combination

Combinations in mathematics are the ways of picking several items from a large group, where order does not matter. For example, there are 6 ways to pick 2 items from a group of 4 items. In mathematics, the number of combinations of picking k items from a group of n items is denoted as , _nC_k, or .

Write a method named getNumberOfCombinations(int n, int k) for computing using following header:

public static BigInteger getNumberOfCombinations(int n, int k)

Write a test program that prompts the user to enter n and k and displays as shown in the following sample run:

Enter n: 4

Enter k: 2

The C(n, k) is 6

Enter n: 500

Enter k: 45

The C(n, k) is 30847877486165278042972675969000464272239600770627726467491808400

Line Editor

Input a String from the user, then input a command to modify the line and finally output the resulting string after performing the command.The commands formats are

Delete: d-

Append: a

Replace: r:

The delete command removes all the characters from the start_index to the end_index (both integers)The first character in the string is start_index is 0. Verify that end_index is greater than the start_index.If the end_index is longer than the length of the string, use the length of the string, Examples

Input String=Ritgers State University

d10-20

OutputStringRitgers Stity

Input String=RitgersState University

d5-11

OutputStringRogete University

Append command just adds the string following the letter a to the end of the current string

Input String=Ritgers State University

as Hillcats

OutputStringRitgers State Universitys Hillcats

Input String=Ritgers State Universitya---Go Cats!

OutputStringRitgers State University---Go Cats!

The replace command matches every occurrence of the first string and replaces it with the second string. There may be multiple matches on one string.The string may contain a space so the separator between the strings is the colon (:)character.It is case sensitive

Input String=Ritgers State University

rer:XXXX

OutputStringRogXXXXs State UnivXXXXsity

Input String=Ritgers State University

rER:XXXXOutputStringRogers State University

Input String=Ritgers State UniversityrUniversity:College

OutputStringRitgers State College

n! Onk!n - k)