给定大小为N的数组,任务是确定是否可以仅通过一次随机排序对数组进行排序。一次混洗中,我们可以将一些连续的元素从数组的末端移开,并将其放置在数组的前面。
例如:
- A = {2, 3, 1, 2}, we can shift {1, 2} from the end of the array to the front of the array to sort it.
- A = {1, 2, 3, 2} since we cannot sort it in one shuffle hence it’s not possible to sort the array.
例子:
Input: arr[] = {1, 2, 3, 4}
Output: Possible
Since this array is already sorted hence no need for shuffle.
Input: arr[] = {6, 8, 1, 2, 5}
Output: Possible
Place last three elements at the front
in the same order i.e. {1, 2, 5, 6, 8}
方法:
- 检查数组是否已经排序。如果是,则返回true。
- 否则开始遍历数组元素,直到当前元素小于下一个元素。将索引存储在arr [i]> arr [i + 1]。
- 从该点开始遍历,并检查该索引元素是否按升序排列。
- 如果同时满足以上两个条件,则检查最后一个元素是否小于或等于给定数组的第一个元素。
- 如果满足以上三个条件,则打印“可能”,否则,如果以上三个条件中的任何一个失败,则打印“不可能”。
下面是上述方法的实现:
C++
// C++ implementation of above approach
#include
using namespace std;
// Function to check if it is possible
bool isPossible(int a[], int n)
{
// step 1
if (is_sorted(a, a + n)) {
cout << "Possible" << endl;
}
else {
// break where a[i] > a[i+1]
bool flag = true;
int i;
for (i = 0; i < n - 1; i++) {
if (a[i] > a[i + 1]) {
break;
}
}
// break point + 1
i++;
// check whether the sequence is
// further increasing or not
for (int k = i; k < n - 1; k++) {
if (a[k] > a[k + 1]) {
flag = false;
break;
}
}
// If not increasing after break point
if (!flag)
return false;
else {
// last element <= First element
if (a[n - 1] <= a[0])
return true;
else
return false;
}
}
}
// Driver code
int main()
{
int arr[] = { 3, 1, 2, 2, 3 };
int n = sizeof(arr) / sizeof(arr[0]);
if (isPossible(arr, n))
cout << "Possible";
else
cout << "Not Possible";
return 0;
}
Java
// Java implementation of above approach
class solution
{
//check if array is sorted
static boolean is_sorted(int a[],int n)
{
int c1=0,c2=0;
//if array is ascending
for(int i=0;i a[i+1]
boolean flag = true;
int i;
for (i = 0; i < n - 1; i++) {
if (a[i] > a[i + 1]) {
break;
}
}
// break point + 1
i++;
// check whether the sequence is
// further increasing or not
for (int k = i; k < n - 1; k++) {
if (a[k] > a[k + 1]) {
flag = false;
break;
}
}
// If not increasing after break point
if (!flag)
return false;
else {
// last element <= First element
if (a[n - 1] <= a[0])
return true;
else
return false;
}
}
return false;
}
// Driver code
public static void main(String[] args)
{
int arr[] = { 3, 1, 2, 2, 3 };
int n = arr.length;
if (isPossible(arr, n))
System.out.println("Possible");
else
System.out.println("Not Possible");
}
}
//contributed by Arnab Kundu
Python 3
# Python 3 implementation of
# above approach
def is_sorted(a):
all(a[i] <= a[i + 1]
for i in range(len(a) - 1))
# Function to check if
# it is possible
def isPossible(a, n):
# step 1
if (is_sorted(a)) :
print("Possible")
else :
# break where a[i] > a[i+1]
flag = True
for i in range(n - 1) :
if (a[i] > a[i + 1]) :
break
# break point + 1
i += 1
# check whether the sequence is
# further increasing or not
for k in range(i, n - 1) :
if (a[k] > a[k + 1]) :
flag = False
break
# If not increasing after
# break point
if (not flag):
return False
else :
# last element <= First element
if (a[n - 1] <= a[0]):
return True
else:
return False
# Driver code
if __name__ == "__main__":
arr = [ 3, 1, 2, 2, 3 ]
n = len(arr)
if (isPossible(arr, n)):
print("Possible")
else:
print("Not Possible")
# This code is contributed
# by ChitraNayal
C#
// C# implementation of above approach
using System;
class GFG
{
// check if array is sorted
static bool is_sorted(int []a, int n)
{
int c1 = 0, c2 = 0;
// if array is ascending
for(int i = 0; i < n - 1; i++)
{
if(a[i] <= a[i + 1])
c1++;
}
// if array is descending
for(int i = 1; i < n; i++)
{
if(a[i] <= a[i - 1])
c2++;
}
if(c1 == n || c2 == n)
return true;
return false;
}
// Function to check if it is possible
static bool isPossible(int []a, int n)
{
// step 1
if (is_sorted(a,n))
{
Console.WriteLine("Possible");
}
else
{
// break where a[i] > a[i+1]
bool flag = true;
int i;
for (i = 0; i < n - 1; i++)
{
if (a[i] > a[i + 1])
{
break;
}
}
// break point + 1
i++;
// check whether the sequence is
// further increasing or not
for (int k = i; k < n - 1; k++)
{
if (a[k] > a[k + 1])
{
flag = false;
break;
}
}
// If not increasing after
// break point
if (!flag)
return false;
else
{
// last element <= First element
if (a[n - 1] <= a[0])
return true;
else
return false;
}
}
return false;
}
// Driver code
public static void Main()
{
int []arr = { 3, 1, 2, 2, 3 };
int n = arr.Length;
if (isPossible(arr, n))
Console.WriteLine("Possible");
else
Console.WriteLine("Not Possible");
}
}
// This code is contributed by anuj_67
PHP
a[i+1]
$flag = true;
$i;
for ($i = 0; $i < $n - 1; $i++)
{
if ($a[$i] > $a[$i + 1])
{
break;
}
}
// break point + 1
$i++;
// check whether the sequence is
// further increasing or not
for ($k = $i; $k < $n - 1; $k++)
{
if ($a[$k] > $a[$k + 1])
{
$flag = false;
break;
}
}
// If not increasing after
// break point
if (!$flag)
return false;
else
{
// last element <= First element
if ($a[$n - 1] <= $a[0])
return true;
else
return false;
}
}
}
// Driver code
$arr = array( 3, 1, 2, 2, 3 );
$n = sizeof($arr);
if (isPossible($arr, $n))
echo "Possible";
else
echo "Not Possible";
// This code is contributed
// by Akanksha Rai(Abby_akku)
?>
Javascript
输出:
Possible