给定一个数组arr[] ,任务是检查是否可以以每个偶数索引(基于 1 的索引)包含偶数的方式重新排列数组。如果这种重新排列是不可能的,打印“否”。否则,打印“是”并打印可能的安排
例子:
Input: arr[] = {2, 4, 8, 3, 1}
Output:
Yes
3 4 8 2 1
Input: arr[] = {3, 3, 11, 8}
Output: No
Explanation: Since, the array contains only one even element, all even indices cannot be filled with a even elements.
方法:
请按照以下步骤解决问题:
- 计算给定数组中存在的偶数元素的总数。如果计数超过给定数组中偶数索引的总数,则打印“否”。
- 否则,打印“是”。现在,使用两个指针i和j遍历数组,分别指向偶数和奇数索引。
- 对于包含奇数元素的任何第i个索引,使用j迭代奇数索引,直到遇到偶数元素。
- 交换a[i]和a[j]
- 重复上述步骤,直到所有偶数索引都被一个偶数元素填充。
下面是上述方法的实现:
C++
// C++ Program to implement
// the above approach
#include
using namespace std;
// Function to check if it the
// array can be rearranged such
// such that every even indices
// contains an even element
void checkPossible(int a[], int n)
{
// Stores the count of even elements
int even_no_count = 0;
// Traverse array to count even numbers
for (int i = 0; i < n; i++)
{
if (a[i] % 2 == 0)
even_no_count++;
}
// If even_no_count exceeds
// count of even indices
if (n / 2 > even_no_count)
{
cout << "No" << endl;
return;
}
cout << "Yes" << endl;
int j = 0;
for (int i = 1; i < n; i += 2)
{
if (a[i] % 2 == 0)
continue;
else
{
while (j < n && a[j] % 2 != 0)
j += 2;
a[i] += a[j];
a[j] = a[i] - a[j];
a[i] -= a[j];
}
}
for (int i = 0; i < n; i++)
{
cout << a[i] << " ";
}
}
// Driver Code
int main()
{
int arr[] = { 2, 3, 4, 5, 6, 7 };
int n = sizeof(arr) / sizeof(arr[0]);
checkPossible(arr, n);
return 0;
}
// This code is contributed by gauravrajput1
Java
// Java Program to implement
// the above approach
import java.io.*;
import java.util.*;
class GFG {
// Function to check if it the
// array can be rearranged such
// such that every even indices
// contains an even element
static void checkPossible(int a[])
{
// Stores the count of even elements
int even_no_count = 0;
// Traverse array to count even numbers
for (int i = 0; i < a.length; i++) {
if (a[i] % 2 == 0)
even_no_count++;
}
// If even_no_count exceeds
// count of even indices
if (a.length / 2 > even_no_count) {
System.out.println("No");
return;
}
System.out.println("Yes");
int j = 0;
for (int i = 1; i < a.length; i += 2) {
if (a[i] % 2 == 0)
continue;
else {
while (j < a.length && a[j] % 2 != 0)
j += 2;
a[i] += a[j];
a[j] = a[i] - a[j];
a[i] -= a[j];
}
}
for (int i = 0; i < a.length; i++) {
System.out.print(a[i] + " ");
}
}
// Driver Code
public static void main(String args[])
{
int arr[] = { 2, 3, 4, 5, 6, 7 };
checkPossible(arr);
}
}
Python3
# Python3 program to implement
# the above approach
# Function to check if it the
# array can be rearranged such
# such that every even indices
# contains an even element
def checkPossible(a, n):
# Stores the count of even elements
even_no_count = 0
# Traverse array to count even numbers
for i in range(n):
if (a[i] % 2 == 0):
even_no_count += 1
# If even_no_count exceeds
# count of even indices
if (n // 2 > even_no_count):
print("No")
return
print("Yes")
j = 0
for i in range(1, n, 2):
if (a[i] % 2 == 0):
continue
else:
while (j < n and a[j] % 2 != 0):
j += 2
a[i] += a[j]
a[j] = a[i] - a[j]
a[i] -= a[j]
for i in range(n):
print(a[i], end = " ")
# Driver Code
arr = [ 2, 3, 4, 5, 6, 7 ]
n = len(arr)
checkPossible(arr, n)
# This code is contributed by code_hunt
C#
// C# Program to implement
// the above approach
using System;
class GFG{
// Function to check if it the
// array can be rearranged such
// such that every even indices
// contains an even element
static void checkPossible(int []a)
{
// Stores the count of even elements
int even_no_count = 0;
// Traverse array to count even numbers
for (int i = 0; i < a.Length; i++)
{
if (a[i] % 2 == 0)
even_no_count++;
}
// If even_no_count exceeds
// count of even indices
if (a.Length / 2 > even_no_count)
{
Console.WriteLine("No");
return;
}
Console.WriteLine("Yes");
int j = 0;
for (int i = 1; i < a.Length; i += 2)
{
if (a[i] % 2 == 0)
continue;
else
{
while (j < a.Length && a[j] % 2 != 0)
j += 2;
a[i] += a[j];
a[j] = a[i] - a[j];
a[i] -= a[j];
}
}
for (int i = 0; i < a.Length; i++)
{
Console.Write(a[i] + " ");
}
}
// Driver Code
public static void Main(String []args)
{
int []arr = { 2, 3, 4, 5, 6, 7 };
checkPossible(arr);
}
}
// This code is contributed by Rajput-Ji
Javascript
输出:
Yes
3 2 5 4 7 6
时间复杂度: O(N)
辅助空间: O(1)
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