Given an array of integers (both odd and even), the task is to arrange them in such a way that odd and even values come in alternate fashion in non-decreasing order(ascending) respectively.
- If the smallest value is Even then we have to print Even-Odd pattern.
- If the smallest value is Odd then we have to print Odd-Even pattern.
Note: No. of odd elements must be equal to No. of even elements in the input array.
Examples:
Input: arr[] = {1, 3, 2, 5, 4, 7, 10}
Output: 1, 2, 3, 4, 5, 10, 7
Smallest value is 1(Odd) so output will be Odd-Even pattern.Input: arr[] = {9, 8, 13, 2, 19, 14}
Output: 2, 9, 8, 13, 14, 19
Smallest value is 2(Even) so output will be Even-Odd pattern.
Asked In: Microsoft Tech-Set-Go-2018
Algorithm:
- Sort the given array.
- Insert Even values in List-1 and Odd values in List-2.
- Now if the smallest value is even, then insert an even value from list 1 and odd value from list 2 to original array and so on.
- But if the smallest value is odd, then insert an odd value from list 2 and even value from list 1 to original array and so on.
Below is the implementation of the above approach:
C++
// C++ implementation of the above approach #include <bits/stdc++.h> using namespace std; void AlternateRearrange(int arr[], int n) { // Sort the array sort(arr, arr + n); vector<int> v1; // to insert even values vector<int> v2; // to insert odd values for (int i = 0; i < n; i++) if (arr[i] % 2 == 0) v1.push_back(arr[i]); else v2.push_back(arr[i]); int index = 0, i = 0, j = 0; bool flag = false; // Set flag to true if first element is even if (arr[0] % 2 == 0) flag = true; // Start rearranging array while (index < n) { // If first element is even if (flag == true) { arr[index++] = v1[i++]; flag = !flag; } // Else, first element is Odd else { arr[index++] = v2[j++]; flag = !flag; } } // Print the rearranged array for (i = 0; i < n; i++) cout << arr[i] << " "; } // Driver code int main() { int arr[] = { 9, 8, 13, 2, 19, 14 }; int n = sizeof(arr) / sizeof(int); AlternateRearrange(arr, n); return 0; } |
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Java
// Java implementation of the above approach import java.util.* ; class GFG { static void AlternateRearrange(int arr[], int n) { // Sort the array // Collection.sort() sorts the // collection in ascending order Arrays.sort(arr) ; Vector v1 = new Vector(); // to insert even values Vector v2 = new Vector(); // to insert odd values for (int i = 0; i < n; i++) if (arr[i] % 2 == 0) v1.add(arr[i]); else v2.add(arr[i]); int index = 0, i = 0, j = 0; boolean flag = false; // Set flag to true if first element is even if (arr[0] % 2 == 0) flag = true; // Start rearranging array while (index < n) { // If first element is even if (flag == true) { arr[index] = (int)v1.get(i); i += 1 ; index += 1 ; flag = !flag; } // Else, first element is Odd else { arr[index] = (int)v2.get(j) ; j += 1 ; index += 1 ; flag = !flag; } } // Print the rearranged array for (i = 0; i < n; i++) System.out.print(arr[i] + " "); } // Driver code public static void main(String []args) { int arr[] = { 9, 8, 13, 2, 19, 14 }; int n = arr.length ; AlternateRearrange(arr, n); } } // This code is contributed by aishwarya.27 |
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Python3
# Python3 implementation of the above approach def AlternateRearrange(arr, n): # Sort the array arr.sort() v1 = list() # to insert even values v2 = list() # to insert odd values for i in range(n): if (arr[i] % 2 == 0): v1.append(arr[i]) else: v2.append(arr[i]) index = 0 i = 0 j = 0 flag = False # Set flag to true if first element is even if (arr[0] % 2 == 0): flag = True # Start rearranging array while (index < n): # If first element is even if (flag == True): arr[index] = v1[i] index += 1 i += 1 flag = ~flag # Else, first element is Odd else: arr[index] = v2[j] index += 1 j += 1 flag = ~flag # Print the rearranged array for i in range(n): print(arr[i], end = " ") # Driver code arr = [ 9, 8, 13, 2, 19, 14] n = len(arr) AlternateRearrange(arr, n) # This code is contributed # by Mohit Kumar 29 |
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C#
// C# implementation of the above approach using System; using System.Collections; class GFG { static void AlternateRearrange(int []arr, int n) { // Sort the array // Collection.sort() sorts the // collection in ascending order Array.Sort(arr) ; ArrayList v1 = new ArrayList(); // to insert even values ArrayList v2 = new ArrayList(); // to insert odd values for (int j = 0; j < n; j++) if (arr[j] % 2 == 0) v1.Add(arr[j]); else v2.Add(arr[j]); int index = 0, i = 0, k = 0; bool flag = false; // Set flag to true if first element is even if (arr[0] % 2 == 0) flag = true; // Start rearranging array while (index < n) { // If first element is even if (flag == true) { arr[index] = (int)v1[i]; i += 1 ; index += 1 ; flag = !flag; } // Else, first element is Odd else { arr[index] = (int)v2[k] ; k += 1 ; index += 1 ; flag = !flag; } } // Print the rearranged array for (i = 0; i < n; i++) Console.Write(arr[i] + " "); } // Driver code static void Main() { int []arr = { 9, 8, 13, 2, 19, 14 }; int n = arr.Length ; AlternateRearrange(arr, n); } } // This code is contributed by mits |
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PHP
<?php // PHP implementation of the above approach function AlternateRearrange($arr, $n) { // Sort the array sort($arr); $v1 = array(); // to insert even values $v2 = array(); // to insert odd values for ($i = 0; $i < $n; $i++) if ($arr[$i] % 2 == 0) array_push($v1, $arr[$i]); else array_push($v2, $arr[$i]); $index = 0; $i = 0; $j = 0; $flag = false; // Set flag to true if first element is even if ($arr[0] % 2 == 0) $flag = true; // Start rearranging array while ($index < $n) { // If first element is even if ($flag == true) { $arr[$index++] = $v1[$i++]; $flag = !$flag; } // Else, first element is Odd else { $arr[$index++] = $v2[$j++]; $flag = !$flag; } } // Print the rearranged array for ($i = 0; $i < $n; $i++) echo $arr[$i], " " ; } // Driver code $arr = array( 9, 8, 13, 2, 19, 14 ); $n = sizeof($arr); AlternateRearrange($arr, $n); // This code is contributed by Ryuga ?> |
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Output:
2 9 8 13 14 19
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