FunctionalOne.java

/**
 * 
 */
package coding.bat.solutions;

import java.util.List;

/**
 * @author Aman Shekhar
 *
 */
public class FunctionalOne {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub

	}

	// --------------------------------------------------------------------------------------------

	// Given a list of integers, return a list where each integer is multiplied by
	// 2.
	//
	//
	// doubling([1, 2, 3]) → [2, 4, 6]
	// doubling([6, 8, 6, 8, -1]) → [12, 16, 12, 16, -2]
	// doubling([]) → []

	public List<Integer> doubling(List<Integer> nums) {
		nums.replaceAll(n -> n * 2);
		return nums;
	}

	// --------------------------------------------------------------------------------------------


	// Given a list of integers, return a list where each integer is multiplied with
	// itself.
	//
	//
	// square([1, 2, 3]) → [1, 4, 9]
	// square([6, 8, -6, -8, 1]) → [36, 64, 36, 64, 1]
	// square([]) → []

	public List<Integer> square(List<Integer> nums) {
		nums.replaceAll(n -> n * n);
		return nums;
	}

	// --------------------------------------------------------------------------------------------


	// Given a list of strings, return a list where each string has "*" added at its
	// end.
	//
	//
	// addStar(["a", "bb", "ccc"]) → ["a*", "bb*", "ccc*"]
	// addStar(["hello", "there"]) → ["hello*", "there*"]
	// addStar(["*"]) → ["**"]

	public List<String> addStar(List<String> strings) {
		strings.replaceAll(n -> n + "*");
		return strings;
	}

	// --------------------------------------------------------------------------------------------


	// Given a list of strings, return a list where each string is replaced by 3
	// copies of the string concatenated together.
	//
	//
	// copies3(["a", "bb", "ccc"]) → ["aaa", "bbbbbb", "ccccccccc"]
	// copies3(["24", "a", ""]) → ["242424", "aaa", ""]
	// copies3(["hello", "there"]) → ["hellohellohello", "theretherethere"]

	public List<String> copies3(List<String> strings) {
		strings.replaceAll(n -> (n + n + n));
		return strings;
	}

	// --------------------------------------------------------------------------------------------


	// Given a list of strings, return a list where each string has "y" added at its
	// start and end.
	//
	//
	// moreY(["a", "b", "c"]) → ["yay", "yby", "ycy"]
	// moreY(["hello", "there"]) → ["yhelloy", "ytherey"]
	// moreY(["yay"]) → ["yyayy"]

	public List<String> moreY(List<String> strings) {
		strings.replaceAll(n -> ("y" + n + "y"));
		return strings;
	}

	// --------------------------------------------------------------------------------------------


	// Given a list of integers, return a list where each integer is added to 1 and
	// the result is multiplied by 10.
	//
	//
	// math1([1, 2, 3]) → [20, 30, 40]
	// math1([6, 8, 6, 8, 1]) → [70, 90, 70, 90, 20]
	// math1([10]) → [110]

	public List<Integer> math1(List<Integer> nums) {
		nums.replaceAll(n -> ((n + 1) * 10));
		return nums;
	}

	// --------------------------------------------------------------------------------------------


	// Given a list of non-negative integers, return an integer list of the
	// rightmost digits. (Note: use %)
	//
	//
	// rightDigit([1, 22, 93]) → [1, 2, 3]
	// rightDigit([16, 8, 886, 8, 1]) → [6, 8, 6, 8, 1]
	// rightDigit([10, 0]) → [0, 0]

	public List<Integer> rightDigit(List<Integer> nums) {
		nums.replaceAll(n -> (n % 10));
		return nums;
	}

	// --------------------------------------------------------------------------------------------


	// Given a list of strings, return a list where each string is converted to
	// lower case (Note: String toLowerCase() method).
	//
	//
	// lower(["Hello", "Hi"]) → ["hello", "hi"]
	// lower(["AAA", "BBB", "ccc"]) → ["aaa", "bbb", "ccc"]
	// lower(["KitteN", "ChocolaTE"]) → ["kitten", "chocolate"]

	public List<String> lower(List<String> strings) {
		strings.replaceAll(n -> n.toLowerCase());
		return strings;
	}

	// --------------------------------------------------------------------------------------------


	// Given a list of strings, return a list where each string has all its "x"
	// removed.
	//
	//
	// noX(["ax", "bb", "cx"]) → ["a", "bb", "c"]
	// noX(["xxax", "xbxbx", "xxcx"]) → ["a", "bb", "c"]
	// noX(["x"]) → [""]

	public List<String> noX(List<String> strings) {
		strings.replaceAll(n -> n.replace("x", ""));
		return strings;
	}					
	
}