CC-19 : Sum of numbers between K1 smallest and K2 smallest.

Description:

Given array of integers, find the K1 smallest and K2 smallest numbers. Then find the sum of all numbers within array in terms of magnitude that are between K1 smallest and K2 smallest numbers.

Test cases and expected outputs:

Input Parameters	Expected outputs
Nums : 1,2,3,4,5,6,7,8,9	Sum between 3rd smallest and 7th smallest number is: 15

Pseudocode:

Method rearrange(str):

This method takes k integer arrays named nums as parameter. We need to find top K1 and K2 smallest integers and value of K1 and K2 are also received as input parameters.

Initialize a PriorityQueue instance named heap. Provide an instance of Collections.reverOrder() to the constructor the PriorityQueue to sort by magnitude of the integers.

Iterate though nums from index 0 to index chars.length-1 using idx as member variable:

Add num[idx] to the heap.

If heapsize is > K2, then remove top element from the heap.

Remove top element from the heap.

Initialize variable sumBetween to 0.

While heap size is > K1:

Remove to element from heap and add it to sumBetween.

Return sumBetween, as now it is the sum of all numbers within array in terms of magnitude that are between K1 smallest and K2 smallest numbers.

Code:

public int sumBetweenK1SmallestAndK2Smallest(int[] nums, int k1, int k2) {
	PriorityQueue<Integer> heap=new PriorityQueue<Integer>(Collections.reverseOrder());
	for (int idx=0; idx<nums.length; idx++) {
		heap.offer(nums[idx]);
		if (heap.size() > k2) {
			heap.poll();
		}
	}	
	heap.poll();
	int sumBetween=0;
	while (heap.size() > k1) {
		sumBetween+=heap.remove();
	}
	return sumBetween;
}

Click here to download and run code and test cases !

Below fully running code can be copied and run on Eclipse or other Java IDEs. Refer the classname in code below. If the class name below is "A", save the code below to a file named A.java before running it. Be sure to try your own test cases to enhance your understanding ! You can also tweak the code to optimize or add enhancements and custom features.

import java.util.Collections;
import java.util.PriorityQueue;

public class HeapSumBetweenK1SmallestAndK2Smallest {
 
public int sumBetweenK1SmallestAndK2Smallest(int[] nums, int k1, int k2) {
	PriorityQueue<Integer> heap=new PriorityQueue<Integer>(Collections.reverseOrder());
	for (int idx=0; idx<nums.length; idx++) {
		heap.offer(nums[idx]);
		if (heap.size() > k2) {
			heap.poll();
		}
	}	
	heap.poll();
	int sumBetween=0;
	while (heap.size() > k1) {
		sumBetween+=heap.remove();
	}
	return sumBetween;
}

public static void printArraySummary(int[] intArray, String label) throws Exception {
   	// Case 1: The input Array is null !!
	if (intArray == null) { System.out.println("\n\n Input Array was null !! \n"); return; }
	// Case 2: Print input Array by index (first to last)
	System.out.println();
	System.out.println("************************************************************************");
	System.out.print(label+" : ");
	int arrayIndex=0;
	for (arrayIndex=0; arrayIndex < intArray.length; arrayIndex++) {
			System.out.print(intArray[arrayIndex]);
			if (arrayIndex < intArray.length-1) {System.out.print(",");}
	} 
	System.out.println();
	System.out.println(" ************************************************************************");
		System.out.println();
		Thread.sleep(2000);
		return;
}


public static void main(String[] args) {
	/***********************
	 Test cases given below:
	 ***********************/
	int retVal;
	try {
	HeapSumBetweenK1SmallestAndK2Smallest hp=new HeapSumBetweenK1SmallestAndK2Smallest();
	int[] nums= {1,2,3,4,5,6,7,8,9} ;
	printArraySummary(nums, "Nums ");
	retVal=hp.sumBetweenK1SmallestAndK2Smallest(nums, 3,7);
	System.out.print("Sum between 3rd smallest and 7th smallest numberis: "+ retVal);	
		
	}catch (Exception exception) {
		System.out.print("Exception: "+ exception);
		exception.printStackTrace();
	}
		
}



}