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Commit e8ae782

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[yuvrajs] Usage of Reduce and examples
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‎README.md

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@@ -5,10 +5,21 @@ Functional programming is a paradigm that allows programming using expressions i
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* [Print each element from list in its own line](src/main/java/com/ysingh/structure/ST01PrintListElement.java)
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* [Print courses, courses having name with Spring, courses having name greater than 3 characters](src/main/java/com/ysingh/structure/ST02CourseExcerise.java)
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* [Print Square of each number in the list](src/main/java/com/ysingh/structure/ST03PrintSquareOfEachListElement.java)
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* [Print sum of all elements in the list](src/main/java/com/ysingh/structure/ST04AddNumbersInList.java)
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* [Print max and min number from all elements in the list](src/main/java/com/ysingh/structure/ST05MaximumAndMinimumNumberInList.java)
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* [Square every number in a list and find the sum of squares](src/main/java/com/ysingh/structure/ST06Excersise.java)
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* [Cube every number in a list and find the sum of cubes](src/main/java/com/ysingh/structure/ST06Excersise.java)
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* [Find sum of odd numbers in a list](src/main/java/com/ysingh/structure/ST06Excersise.java)
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## Implementations using Functional Programming
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### Using Streams, Filters and Lambdas:
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* [Print each element from list in its own line](/src/main/java/com/ysingh/functional/FP01PrintListElement.java)
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* [Print courses, courses having name with Spring, courses having name greater than 3 characters](src/main/java/com/ysingh/functional/FP02CourseExcerise.java)
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### Using Map:
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* [Print Square of each number in the list](src/main/java/com/ysingh/functional/FP03PrintSquareOfEachListElement.java)
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* [Print Square of each number in the list](src/main/java/com/ysingh/functional/FP03PrintSquareOfEachListElement.java)
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### Using Reduce:
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* [Print sum of all elements in the list](src/main/java/com/ysingh/functional/FP04AddNumbersInList.java)
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* [Print max and min number from all elements in the list](src/main/java/com/ysingh/functional/FP05MaximumAndMinimumNumberInList.java)
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* [Square every number in a list and find the sum of squares](src/main/java/com/ysingh/functional/FP06Excersise.java)
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* [Cube every number in a list and find the sum of cubes](src/main/java/com/ysingh/functional/FP06Excersise.java)
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* [Find sum of odd numbers in a list](src/main/java/com/ysingh/functional/FP06Excersise.java)
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package com.ysingh.functional;
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import java.util.Arrays;
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import java.util.List;
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public class FP04AddNumbersInList {
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public static void main(String args[]) {
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List<Integer> numbers = Arrays.asList(12,9,13,5,4,2,4,12,15);
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System.out.println("Calculating Sum of All Numbers: ");
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int sum = addListNumbers(numbers);
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System.out.println(sum);
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}
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private static int addListNumbers(List<Integer> numbers) {
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return numbers.stream().reduce(0, (num1, num2) -> num1 + num2);
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}
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}
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package com.ysingh.functional;
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import java.util.Arrays;
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import java.util.List;
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public class FP05MaximumAndMinimumNumberInList {
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public static void main(String args[]) {
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List<Integer> numbers = Arrays.asList(12,9,13,5,4,2,4,12,15);
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System.out.println("Calculating Max Number from All Numbers: ");
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int max = maxInListNumbers(numbers);
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System.out.println(max);
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System.out.println();
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System.out.println("Calculating Min Number from All Numbers: ");
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int min = minInListNumbers(numbers);
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System.out.println(min);
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}
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private static int maxInListNumbers(List<Integer> numbers) {
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return numbers.stream().reduce(Integer.MIN_VALUE, (num1, num2) -> num1 > num2 ? num1 : num2);
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}
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private static int minInListNumbers(List<Integer> numbers) {
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return numbers.stream().reduce(Integer.MAX_VALUE, (num1, num2) -> num1 > num2 ? num2 : num1);
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}
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}
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package com.ysingh.functional;
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import java.util.Arrays;
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import java.util.List;
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public class FP06Excersise {
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public static void main(String args[]) {
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List<Integer> numbers = Arrays.asList(12,9,13,5,4,2,4,12,15);
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System.out.println("Square Each Number and Print Sum:");
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int sum = squareNumbersInListAndPrintSum(numbers);
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System.out.println(sum);
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System.out.println();
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System.out.println("Cube Each Number and Print Sum:");
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sum = cubeNumbersInListAndPrintSum(numbers);
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System.out.println(sum);
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System.out.println();
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System.out.println("Sum of Odd Numbers in the list:");
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sum = sumOfOddNumbersInList(numbers);
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System.out.println(sum);
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System.out.println();
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}
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private static int squareNumbersInListAndPrintSum(List<Integer> numbers) {
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return numbers.stream().map(number -> number * number).reduce(0, (num1, num2) -> num1 + num2);
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}
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private static int cubeNumbersInListAndPrintSum(List<Integer> numbers) {
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return numbers.stream().map(number -> number * number * number).reduce(0, (num1, num2) -> num1 + num2);
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}
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private static int sumOfOddNumbersInList(List<Integer> numbers) {
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return numbers.stream().filter(number -> number % 2 != 0).reduce(0, (num1, num2) -> num1 + num2);
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}
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}
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package com.ysingh.structure;
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import java.util.Arrays;
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import java.util.List;
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public class ST04AddNumbersInList {
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public static void main(String args[]) {
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List<Integer> numbers = Arrays.asList(12,9,13,5,4,2,4,12,15);
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System.out.println("Calculating Sum of All Numbers: ");
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int sum = addListNumbers(numbers);
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System.out.println(sum);
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}
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private static int addListNumbers(List<Integer> numbers) {
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int sum = 0;
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for(int number : numbers) {
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sum = sum + number;
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}
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return sum;
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}
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}
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package com.ysingh.structure;
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import java.util.Arrays;
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import java.util.List;
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public class ST05MaximumAndMinimumNumberInList {
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public static void main(String args[]) {
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List<Integer> numbers = Arrays.asList(12,9,13,5,4,2,4,12,15);
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System.out.println("Calculating Max Number from All Numbers: ");
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int max = maxInListNumbers(numbers);
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System.out.println(max);
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System.out.println();
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System.out.println("Calculating Min Number from All Numbers: ");
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int min = minInListNumbers(numbers);
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System.out.println(min);
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}
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private static int maxInListNumbers(List<Integer> numbers) {
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int max = Integer.MIN_VALUE;
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for(int number : numbers) {
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if(number > max) {
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max = number;
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}
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}
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return max;
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}
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private static int minInListNumbers(List<Integer> numbers) {
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int min = Integer.MAX_VALUE;
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for(int number : numbers) {
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if(number < min) {
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min = number;
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}
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}
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return min;
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}
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}
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package com.ysingh.structure;
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import java.util.Arrays;
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import java.util.List;
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public class ST06Excersise {
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public static void main(String args[]) {
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List<Integer> numbers = Arrays.asList(12,9,13,5,4,2,4,12,15);
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System.out.println("Square Each Number and Print Sum:");
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int sum = squareNumbersInListAndPrintSum(numbers);
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System.out.println(sum);
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System.out.println();
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System.out.println("Cube Each Number and Print Sum:");
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sum = cubeNumbersInListAndPrintSum(numbers);
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System.out.println(sum);
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System.out.println();
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System.out.println("Sum of Odd Numbers in the list:");
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sum = sumOfOddNumbersInList(numbers);
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System.out.println(sum);
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System.out.println();
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}
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private static int squareNumbersInListAndPrintSum(List<Integer> numbers) {
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int sum = 0;
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for(int number : numbers) {
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sum = sum + (number * number);
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}
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return sum;
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}
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private static int cubeNumbersInListAndPrintSum(List<Integer> numbers) {
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int sum = 0;
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for(int number : numbers) {
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sum = sum + (number * number * number);
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}
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return sum;
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}
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private static int sumOfOddNumbersInList(List<Integer> numbers) {
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int sum = 0;
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for(int number : numbers) {
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if(number % 2 != 0) {
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sum = sum + number;
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}
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}
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return sum;
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}
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}

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