正数元素位于偶数位置，负数元素位于奇数位置（不保持相对顺序）
原文： https://www.geeksforgeeks.org/positive-elements-even-negative-odd-positions/
给您一个数组，您必须编写一个程序来转换该数组，以使正元素出现在数组的偶数位置，而负元素出现在数组的奇数位置。 我们必须做到这一点。
正值和负值的数目可能不相等，多余的值必须保持原样。
示例：
Input : arr[] = {1, -3, 5, 6, -3, 6, 7, -4, 9, 10}
Output : arr[] = {1, -3, 5, -3, 6, 6, 7, -4, 9, 10}
Input : arr[] = {-1, 3, -5, 6, 3, 6, -7, -4, -9, 10}
Output : arr[] = {3, -1, 6, -5, 3, -7, 6, -4, 10, -9}
我们采用正面和负面两个指标。 我们将正指针设置在数组的开头，将负指针设置在数组的第一个位置。
我们将正指针向前移动两步，直到找到负元素。 同样，我们将负指针向前移动两个位置，直到在其位置找到正值。
如果正负指针位于数组中，则我们将交换这些索引处的值，否则将停止执行该过程。
C++
// C++ program to rearrange positive and negative
// numbers
#include <bits/stdc++.h>
using namespace std;
void rearrange(int a[], int size)
{
int positive = 0, negative = 1;
while (true) {
/* Move forward the positive pointer till
negative number number not encountered */
while (positive < size && a[positive] >= 0)
positive += 2;
/* Move forward the negative pointer till
positive number number not encountered */
while (negative < size && a[negative] <= 0)
negative += 2;
// Swap array elements to fix their position.
if (positive < size && negative < size)
swap(a[positive], a[negative]);
/* Break from the while loop when any index
exceeds the size of the array */
else
break;
}
}
// Driver code
int main()
{
int arr[] = { 1, -3, 5, 6, -3, 6, 7, -4, 9, 10 };
int n = (sizeof(arr) / sizeof(arr[0]));
rearrange(arr, n);
for (int i = 0; i < n; i++)
cout << arr[i] << " ";
return 0;
}
Java
// Java program to rearrange positive
// and negative numbers
import java.io.*;
class GFG {
static void rearrange(int a[], int size)
{
int positive = 0, negative = 1, temp;
while (true) {
/* Move forward the positive pointer till
negative number number not encountered */
while (positive < size && a[positive] >= 0)
positive += 2;
/* Move forward the negative pointer till
positive number number not encountered */
while (negative < size && a[negative] <= 0)
negative += 2;
// Swap array elements to fix their position.
if (positive < size && negative < size) {
temp = a[positive];
a[positive] = a[negative];
a[negative] = temp;
}
/* Break from the while loop when any index
exceeds the size of the array */
else
break;
}
}
// Driver code
public static void main(String args[]) {
int arr[] = {1, -3, 5, 6, -3, 6, 7, -4, 9, 10};
int n = arr.length;
rearrange(arr, n);
for (int i = 0; i < n; i++)
System.out.print(arr[i] + " ");
}
}
/*This code is contributed by Nikita Tiwari.*/
Python3
# Python 3 program to rearrange
# positive and negative numbers
def rearrange(a, size) :
positive = 0
negative = 1
while (True) :
# Move forward the positive
# pointer till negative number
# number not encountered
while (positive < size and a[positive] >= 0) :
positive = positive + 2
# Move forward the negative
# pointer till positive number
# number not encountered
while (negative < size and a[negative] <= 0) :
negative = negative + 2
# Swap array elements to fix
# their position.
if (positive < size and negative < size) :
temp = a[positive]
a[positive] = a[negative]
a[negative] = temp
# Break from the while loop when
# any index exceeds the size of
# the array
else :
break
# Driver code
arr =[ 1, -3, 5, 6, -3, 6, 7, -4, 9, 10 ]
n = len(arr)
rearrange(arr, n)
for i in range(0, n) :
print(arr[i], end = " ")
# This code is contributed by Nikita Tiwari.
C#
// C# program to rearrange positive
// and negative numbers
using System;
class GFG {
// Function to rearrange
static void rearrange(int []a, int size)
{
int positive = 0, negative = 1, temp;
while (true) {
// Move forward the positive pointer till
// negative number number not encountered
while (positive < size && a[positive] >= 0)
positive += 2;
// Move forward the negative pointer till
// positive number number not encountered
while (negative < size && a[negative] <= 0)
negative += 2;
// Swap array elements to fix their position.
if (positive < size && negative < size) {
temp = a[positive];
a[positive] = a[negative];
a[negative] = temp;
}
// Break from the while loop when any
// index exceeds the size of the array
else
break;
}
}
// Driver Code
public static void Main(String []args) {
int []arr = {1, -3, 5, 6, -3, 6, 7, -4, 9, 10};
int n = arr.Length;
rearrange(arr, n);
for (int i = 0; i < n; i++)
Console.Write(arr[i] + " ");
}
}
// This code is contributed by Nitin Mittal.
PHP
<?php
// PHP program to rearrange positive
// and negative numbers
function rearrange(&$a, $size)
{
$positive = 0;
$negative = 1;
while (true)
{
/* Move forward the positive
pointer till negative number
number not encountered */
while ($positive < $size &&
$a[$positive] >= 0)
$positive += 2;
/* Move forward the negative
pointer till positive number
number not encountered */
while ($negative < $size &&
$a[$negative] <= 0)
$negative += 2;
// Swap array elements to fix
// their position.
if ($positive < $size &&
$negative < $size)
{
$temp = $a[$positive];
$a[$positive] = $a[$negative];
$a[$negative] = $temp;
}
/* Break from the while loop
when any index exceeds the
size of the array */
else
break;
}
}
// Driver code
$arr = array( 1, -3, 5, 6, -3,
6, 7, -4, 9, 10 );
$n = sizeof($arr);
rearrange($arr, $n);
for ($i = 0; $i < $n; $i++)
echo $arr[$i] ." ";
// This code is contributed by ChitraNayal
?>
输出：
1 -3 5 -3 6 6 7 -4 9 10
让我们在第一个示例上解释代码的工作。
arr[] = {1, -3, 5, 6, -3, 6, 7, -4, 9, 10}
我们声明两个变量为正负，正数指向第零个位置，负数指向第一个位置。
正= 0，负数= 1，
在第一次迭代中，由于a[4]小于零且正数= 4，正数会将 4 个位置移至第五个位置。
负数将移动 2 个位置，并以a[3] > 0指向第四位置。
我们将交换正和负位置值，因为它们小于数组的大小。
第一次迭代后，数组变为arr[] = {1, -3, 5, -3, 6, 6, 7, -4, 9, 10}。
现在在第四位置的正点和在第三位置的负点。
在第二次迭代中，正值将移动 6 位，其值将比数组的大小大。
负指针将向前移动两步，并将指向第五个位置。
当正指针值变得大于数组大小时，我们将不执行任何交换操作并退出while循环。
最终输出为arr[] = {1, -3, 5, -3, 6, 6, 7, -4, 9, 10}。
不维持相对顺序的示例：
{-1, -2, -3, -4, -5, 6, 7, 8};
另一种方法：
想法是找到一个不正确位置的正/负元素（即，在奇数位置为正，在偶数位置为负），然后找到符号相反的元素，即在剩余数组中的错误位置，然后交换这两个元素。
这是上述想法的实现。
C++
// C++ program to rearrange positive
// and negative numbers
#include<iostream>
using namespace std;
// Swap function
void swap(int* a, int i , int j)
{
int temp = a[i];
a[i] = a[j];
a[j] = temp;
return ;
}
// Print array function
void printArray(int* a, int n)
{
for(int i = 0; i < n; i++)
cout << a[i] << " ";
cout << endl;
return ;
}
// Driver code
int main()
{
int arr[] = { 1, -3, 5, 6, -3, 6, 7, -4, 9, 10 };
int n = sizeof(arr)/sizeof(arr[0]);
//before modification
printArray(arr, n);
for(int i = 0; i < n; i++)
{
if(arr[i] >= 0 && i % 2 == 1)
{
// out of order positive element
for(int j = i + 1; j < n; j++)
{
if(arr[j] < 0 && j % 2 == 0)
{
// find out of order negative
// element in remaining array
swap(arr, i, j);
break ;
}
}
}
else if(arr[i] < 0 && i % 2 == 0)
{
// out of order negative element
for(int j = i + 1; j < n; j++)
{
if(arr[j] >= 0 && j % 2 == 1)
{
// find out of order positive
// element in remaining array
swap(arr, i, j);
break;
}
}
}
}
//after modification
printArray(arr, n);
return 0;
}
// This code is contributed by AnitAggarwal
Java
// Java program to rearrange positive
// and negative numbers
import java.io.*;
import java.util.*;
class GFG
{
// Swap function
static void swap(int[] a, int i, int j)
{
int temp = a[i];
a[i] = a[j];
a[j] = temp;
}
// Print array function
static void printArray(int[] a, int n)
{
for (int i = 0; i < n; i++)
System.out.print(a[i] + " ");
System.out.println();
}
// Driver code
public static void main(String args[])
{
int[] arr = { 1, -3, 5, 6, -3, 6, 7, -4, 9, 10 };
int n = arr.length;
//before modification
printArray(arr, n);
for (int i = 0; i < n; i++)
{
if (arr[i] >= 0 && i % 2 == 1)
{
// out of order positive element
for (int j = i + 1; j < n; j++)
{
if (arr[j] < 0 && j % 2 == 0)
{
// find out of order negative
// element in remaining array
swap(arr, i, j);
break ;
}
}
}
else if (arr[i] < 0 && i % 2 == 0)
{
// out of order negative element
for (int j = i + 1; j < n; j++)
{
if (arr[j] >= 0 && j % 2 == 1)
{
// find out of order positive
// element in remaining array
swap(arr, i, j);
break;
}
}
}
}
//after modification
printArray(arr, n);
}
}
// This code is contributed by rachana soma
Python3
# Python3 program to rearrange positive
# and negative numbers
# Print array function
def printArray(a, n):
for i in a:
print(i, end = " ")
print()
# Driver code
arr = [1, -3, 5, 6, -3, 6, 7, -4, 9, 10]
n = len(arr)
# before modification
printArray(arr, n)
for i in range(n):
if(arr[i] >= 0 and i % 2 == 1):
# out of order positive element
for j in range(i + 1, n):
if(arr[j] < 0 and j % 2 == 0):
# find out of order negative
# element in remaining array
arr[i], arr[j] = arr[j], arr[i]
break
elif (arr[i] < 0 and i % 2 == 0):
# out of order negative element
for j in range(i + 1, n):
if(arr[j] >= 0 and j % 2 == 1):
# find out of order positive
# element in remaining array
arr[i], arr[j] = arr[j], arr[i]
break
# after modification
printArray(arr, n);
# This code is contributed
# by mohit kumar
C
// C# program to rearrange positive
// and negative numbers
using System;
class GFG
{
// Swap function
static void swap(int[] a, int i, int j)
{
int temp = a[i];
a[i] = a[j];
a[j] = temp;
}
// Print array function
static void printArray(int[] a, int n)
{
for (int i = 0; i < n; i++)
Console.Write(a[i] + " ");
Console.WriteLine();
}
// Driver code
public static void Main()
{
int[] arr = { 1, -3, 5, 6, -3, 6, 7, -4, 9, 10 };
int n = arr.Length;
//before modification
printArray(arr, n);
for (int i = 0; i < n; i++)
{
if (arr[i] >= 0 && i % 2 == 1)
{
// out of order positive element
for (int j = i + 1; j < n; j++)
{
if (arr[j] < 0 && j % 2 == 0)
{
// find out of order negative
// element in remaining array
swap(arr, i, j);
break ;
}
}
}
else if (arr[i] < 0 && i % 2 == 0)
{
// out of order negative element
for (int j = i + 1; j < n; j++)
{
if (arr[j] >= 0 && j % 2 == 1)
{
// find out of order positive
// element in remaining array
swap(arr, i, j);
break;
}
}
}
}
// after modification
printArray(arr, n);
}
}
// This code is contributed by Akanksha Rai
输出：
1 -3 5 6 -3 6 7 -4 9 10
1 -3 5 -3 6 6 7 -4 9 10
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