Timesort.java

class GFG
{

	static int MIN_MERGE = 32;

	public static int minRunLength(int n)
	{
		assert n >= 0;
	
		// Becomes 1 if any 1 bits are shifted off
		int r = 0;
		while (n >= MIN_MERGE)
		{
			r |= (n & 1);
			n >>= 1;
		}
		return n + r;
	}


	public static void insertionSort(int[] arr, int left,
									int right)
	{
		for (int i = left + 1; i <= right; i++)
		{
			int temp = arr[i];
			int j = i - 1;
			while (j >= left && arr[j] > temp)
			{
				arr[j + 1] = arr[j];
				j--;
			}
			arr[j + 1] = temp;
		}
	}

	// Merge function merges the sorted runs
	public static void merge(int[] arr, int l,
								int m, int r)
	{
		// Original array is broken in two parts
		// left and right array
		int len1 = m - l + 1, len2 = r - m;
		int[] left = new int[len1];
		int[] right = new int[len2];
		for (int x = 0; x < len1; x++)
		{
			left[x] = arr[l + x];
		}
		for (int x = 0; x < len2; x++)
		{
			right[x] = arr[m + 1 + x];
		}

		int i = 0;
		int j = 0;
		int k = l;

		while (i < len1 && j < len2)
		{
			if (left[i] <= right[j])
			{
				arr[k] = left[i];
				i++;
			}
			else {
				arr[k] = right[j];
				j++;
			}
			k++;
		}

		while (i < len1)
		{
			arr[k] = left[i];
			k++;
			i++;
		}

		while (j < len2)
		{
			arr[k] = right[j];
			k++;
			j++;
		}
	}

	public static void timSort(int[] arr, int n)
	{
		int minRun = minRunLength(MIN_MERGE);
	
		// Sort individual subarrays of size RUN
		for (int i = 0; i < n; i += minRun)
		{
			insertionSort(arr, i,
						Math.min((i + MIN_MERGE - 1), (n - 1)));
		}

		
		for (int size = minRun; size < n; size = 2 * size)
		{
			for (int left = 0; left < n;
								left += 2 * size)
			{

				int mid = left + size - 1;
				int right = Math.min((left + 2 * size - 1),
									(n - 1));

				if(mid < right)
					merge(arr, left, mid, right);
			}
		}
	}

	// Utility function to print the Array
	public static void printArray(int[] arr, int n)
	{
		for (int i = 0; i < n; i++) {
			System.out.print(arr[i] + " ");
		}
		System.out.print("\n");
	}

	// Driver code
	public static void main(String[] args)
	{
		int[] arr = { -2, 7, 15, -14, 0, 15, 0, 7,
					-7, -4, -13, 5, 8, -14, 12 };
		int n = arr.length;
		System.out.println("Given Array is");
		printArray(arr, n);

		timSort(arr, n);

		System.out.println("After Sorting Array is");
		printArray(arr, n);
	}
}