Update kadanes.java

Author: inimitable034

Arrays/kadanes.java

@@ -1,5 +1,12 @@
 // Java program for Kadane's Algorithms
-// 
+
+//### Description :-
+
+//The  idea behind the implementation of Kadane’s algorithm is to peek for all positive contiguous segments of the array (max_ending_here is used for this).
+//Keep track of  the maximum sum contiguous segment among all positive segments (max_so_far is used for this).
+//Each time we get a positive-sum compare it with max_so_far and update max_so_far if it is greater than max_so_far.
+
+
 class algo{
 
 	static void Kadanes(int a[], int size)
@@ -10,9 +17,11 @@ static void Kadanes(int a[], int size)
 
 		for (int i = 0; i < size; i++)
 		{
+		// loop to iterate and find the max_ending_here.
 			max_ending_here += a[i];
 
 			if (max_so_far < max_ending_here)
+		//condition to find the start and end indexes of the sub-array
 			{
 				max_so_far = max_ending_here;
 				start = s;
@@ -25,6 +34,7 @@ static void Kadanes(int a[], int size)
 				s = i + 1;
 			}
 		}
+		// PRINT THE MAXIMUM CONTIGUOUS SUM WITH THE STARTING AND ENDING INDEXES.
 		System.out.println("Maximum contiguous sum is "
 						+ max_so_far);
 		System.out.println("Starting index " + start);
@@ -36,7 +46,52 @@ public static void main(String[] args)
 	{
 		int a[] = { 10, 16, -2, 8, 5, 9, -7, 3 };
 		int n = a.length;
+	// CALLING OUR FUNCTION TO IMPLEMENT THE ALGORITH ON THE ABOVE ARRAY a[] 
 		Kadanes(a, n);
 	}
 }
+//     A SAMPLE TEST CASE  :-
+
+//     Here is a test cases to show the implementation of the above stated Algorithm:-
+
+//     Lets take the below set of elements in an array as example:
+//     {-2, -3, 4, -1, -2, 1, 5, -3}
+
+//     max_so_far = max_ending_here = 0
+
+//     for i=0,  a[0] =  -2
+//     max_ending_here = max_ending_here + (-2)
+//     Set max_ending_here = 0 because max_ending_here < 0
+
+//     for i=1,  a[1] =  -3
+//     max_ending_here = max_ending_here + (-3)
+//     Set max_ending_here = 0 because max_ending_here < 0
+
+//     for i=2,  a[2] =  4
+//     max_ending_here = max_ending_here + (4)
+//     max_ending_here = 4
+//     max_so_far is updated to 4 because max_ending_here greater 
+//     than max_so_far which was 0 till now
+
+//     for i=3,  a[3] =  -1
+//     max_ending_here = max_ending_here + (-1)
+//     max_ending_here = 3
+
+//     for i=4,  a[4] =  -2
+//     max_ending_here = max_ending_here + (-2)
+//     max_ending_here = 1
+
+//     for i=5,  a[5] =  1
+//     max_ending_here = max_ending_here + (1)
+//     max_ending_here = 2
+
+//     for i=6,  a[6] =  5
+//     max_ending_here = max_ending_here + (5)
+//     max_ending_here = 7
+//     max_so_far is updated to 7 because max_ending_here is 
+//     greater than max_so_far
+
+//     for i=7,  a[7] =  -3
+//     max_ending_here = max_ending_here + (-3)
+//     max_ending_here = 4