KadaneAlgorithm.java

import java.util.Scanner;

/**
 * Program to implement Kadane’s Algorithm to 
 * calculate maximum contiguous subarray sum of an array
 * Time Complexity: O(n)
 * 
 * @author Nishita Aggarwal
 *
 */

public class KadaneAlgorithm {
	
	/**
	* This method implements Kadane's Algorithm
	* 
        * @param arr The input array
	* @return The maximum contiguous subarray sum of the array
        * 
        */
	static int largestContiguousSum(int arr[]){
		int i,len=arr.length,cursum=0,maxsum=Integer.MIN_VALUE;
		if(len==0)	//empty array
			return 0;
		for(i=0;i<len;i++){
			cursum+=arr[i];
			if(cursum>maxsum){
				maxsum=cursum;
			}
			if(cursum<=0){
				cursum=0;
			}
		}
		return maxsum;
	}

	/**
	 * Main method
	 * 
	 * @param args Command line arguments
	 */
	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		int n,arr[],i;
		n=sc.nextInt();
		arr=new int[n];
		for(i=0;i<n;i++){
			arr[i]=sc.nextInt();
		}
		int maxContSum=largestContiguousSum(arr);
		System.out.println(maxContSum);
		sc.close();
	}

}