PancakeSort.java

src/java/main/PancakeSort.java

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+import java.io.*; 
+
+class PancakeSort { 
+
+	/* Reverses arr[0..i] */
+	static void flip(int arr[], int i) 
+	{ 
+		int temp, start = 0; 
+		while (start < i) 
+		{ 
+			temp = arr[start]; 
+			arr[start] = arr[i]; 
+			arr[i] = temp; 
+			start++; 
+			i--; 
+		} 
+	} 
+
+	// Returns index of the 
+	// maximum element in 
+	// arr[0..n-1] 
+	static int findMax(int arr[], int n) 
+	{ 
+		int mi, i; 
+		for (mi = 0, i = 0; i < n; ++i) 
+			if (arr[i] > arr[mi]) 
+				mi = i; 
+		return mi; 
+	} 
+
+	// The main function that 
+	// sorts given array using 
+	// flip operations 
+	static int pancakeSort(int arr[], int n) 
+	{ 
+		// Start from the complete 
+		// array and one by one 
+		// reduce current size by one 
+		for (int curr_size = n; curr_size > 1; --curr_size) 
+		{ 
+			// Find index of the 
+			// maximum element in 
+			// arr[0..curr_size-1] 
+			int mi = findMax(arr, curr_size); 
+
+			// Move the maximum element 
+			// to end of current array 
+			// if it's not already at 
+			// the end 
+			if (mi != curr_size-1) 
+			{ 
+				// To move at the end, 
+				// first move maximum 
+				// number to beginning 
+				flip(arr, mi); 
+
+				// Now move the maximum 
+				// number to end by 
+				// reversing current array 
+				flip(arr, curr_size-1); 
+			} 
+		} 
+		return 0; 
+	} 
+
+	/* Utility function to print array arr[] */
+	static void printArray(int arr[], int arr_size) 
+	{ 
+		for (int i = 0; i < arr_size; i++) 
+			System.out.print(arr[i] + " "); 
+		System.out.println(""); 
+	} 
+
+	/* Driver function to check for above functions*/
+	public static void main (String[] args) 
+	{ 
+		int arr[] = {23, 10, 20, 11, 12, 6, 7}; 
+		int n = arr.length; 
+
+		pancakeSort(arr, n); 
+
+		System.out.println("Sorted Array: "); 
+		printArray(arr, n); 
+	} 
+}