TimSort.java

Java/TimSort.java

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+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;
+	}// This function sorts array from left index to right index which is of size atmost RUN
+	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;
+    // After comparing, we merge those two array in larger sub array
+		while (i < len1 && j < len2)
+		{	if (left[i] <= right[j])
+			{ arr[k] = left[i];
+				i++;
+			}
+			else {
+				arr[k] = right[j];
+				j++;
+			}
+			k++;
+		}
+    // Copy remaining elements of left, if any
+		while (i < len1)
+		{arr[k] = left[i];
+			k++;
+			i++;
+		}
+// Copy remaining element of right, if any
+		while (j < len2)
+		{ arr[k] = right[j];
+			k++;
+			j++;
+		}}
+	// Iterative Timsort function to sort the array[0...n-1] (similar to merge sort)
+	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)));
+		}
+    // Start merging from size RUN (or 32).
+		for (int size = minRun; size < n; size = 2 * size)
+		{ // Pick starting point of left sub array
+			//  merge arr[left..left+size-1] and arr[left+size, left+2*size-1]
+			for (int left = 0; left < n;
+								left += 2 * size)
+      { // Find ending point of left sub array
+				// mid+1 is starting point of right subarray
+				int mid = left + size - 1;
+				int right = Math.min((left + 2 * size - 1),
+									(n - 1));
+  	// Merge sub array arr[left.....mid] & arr[mid+1....right]
+				if(mid < right)
+					merge(arr, left, mid, right);
+			} }	}
+	// Utility function to print the Array
+	public static void printArra(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);
+	}}