## Hackerrank - Almost Sorted Solution

Given an array of integers, determine whether the array can be sorted in *ascending order* using only one of the following operations one time.

- Swap two elements.
- Reverse one sub-segment.

Determine whether one, both or neither of the operations will complete the task. If both work, choose *swap*. For instance, given an array either swap the and , or reverse them to sort the array. Choose swap. The Output Format section below details requirements.

**Function Description**

Complete the *almostSorted* function in the editor below. It should print the results and return nothing.

almostSorted has the following parameter(s):

*arr*: an array of integers

**Input Format**

The first line contains a single integer , the size of .

The next line contains space-separated integers where .

**Constraints**

All are distinct.

**Output Format**

- If the array is already sorted, output
*yes*on the first line. You do not need to output anything else.

If you can sort this array using one single operation (from the two permitted operations) then output *yes* on the first line and then:

**a.** If elements can be swapped, and , output *swap l r* in the second line. and are the indices of the elements to be swapped, assuming that the array is indexed from to .

**b.** Otherwise, when reversing the segment , output *reverse l r* in the second line. and are the indices of the first and last elements of the subsequence to be reversed, assuming that the array is indexed from to .

represents the sub-sequence of the array, beginning at index and ending at index , both inclusive.

If an array can be sorted by either swapping or reversing, choose swap.

- If you cannot sort the array either way, output
*no*on the first line.

**Sample Input 1**

```
2
4 2
```

**Sample Output 1**

```
yes
swap 1 2
```

**Explanation 1**

You can either *swap(1, 2)* or *reverse(1, 2)*. You prefer swap.

**Sample Input 2**

```
3
3 1 2
```

**Sample Output 2**

```
no
```

**Explanation 2**

It is impossible to sort by one single operation.

**Sample Input 3**

```
6
1 5 4 3 2 6
```

**Sample Output 3**

```
yes
reverse 2 5
```

**Explanation 3**

You can reverse the sub-array *d[2...5] = "5 4 3 2"*, then the array becomes sorted.

### Solution in Python

```
def almostSorted(a):
x = 0
y = len(a)-1
while a[x]<=a[x+1]:
x+=1
while a[y]>=a[y-1]:
y-=1
b = a[x:y+1]
b[0],b[-1]=b[-1],b[0]
cond_l = True if x-1<0 else b[0]>=a[x-1]
cond_r = True if y+1==len(a) else a[y+1]>=b[-1]
if cond_l and cond_r:
for i in range(len(b)-1):
if b[i]>b[i+1]:
break
else:
return "yes\nswap %s %s"%(x+1,y+1)
b[0],b[-1]=b[-1],b[0]
cond_l = True if x-1<0 else a[x-1]<=b[-1]
cond_r = True if y+1==len(a) else b[0]<=a[y+1]
if cond_l and cond_r:
for i in range(len(b)-1):
if b[i]<b[i+1]:
break
else:
return "yes\nreverse %s %s"%(x+1,y+1)
return "no"
n = int(input())
arr = list(map(int, input().split()))
print(almostSorted(arr))
```