LongestSubArray.java

/*
1. Longest Subarray With Sum ≤ K
Description:
Given an integer list nums and integer k, return the maximum length of a contiguous subarray whose sum is ≤ k.
Example:
Input: nums=[2,3,1,2,4], k=7
Output: 3
Explanation: [3,1,2] has sum 6 ≤ 7.
*/
import java.util.*;
public class LongestSubArray
{
	public static void main(String x[])
	{
		Scanner sc = new Scanner(System.in); 
		// take array list from user
		System.out.print("Enter the total elements count: ");
		int size = sc.nextInt(); // use loop for total values insert into a arraylist
		ArrayList num = new ArrayList();
		for(int i = 1; i <= size; i++)
		{
			int number = sc.nextInt();
			num.add(number);
		}
		// taking the value of k 
		System.out.print("Enter the value of K: ");
		int k = sc.nextInt();
		// using two pointer techniques
		int maxLen = 0; // store the min length of subarray
		int sum = 0;
		int s = 0;
		int e = 0;
		while(s < num.size())
		{
			sum += (int)num.get(s);
			if(sum <= k) // checking the sum is <= k if yes then check inner condition of max length
			{
				if((s-e+1)> maxLen)
				{
					maxLen = s-e+1;
				}
			}
			while(sum > k) // if sum is > k then remove last elements from subarray
			{
				sum -= (int)num.get(e);
				e++; // shift index or increase index by 1
				if(sum <= k) // checking  sum is <= k if yes then store max length
				{
					if(s-e+1> maxLen)
					{
						maxLen = s-e+1;
					}
				}
			}
			s++;
		}
		System.out.println("Max Length is: "+maxLen); // print max subarray with sum is less than equal to k 
	}
}