﻿ C : Minimum length of a subarray to make the whole array

# C Exercises: Find the minimum length of subarray such that, sorting this subarray makes the whole array sorted

## C Array: Exercise-91 with Solution

An unsorted array of a specific size is given. Write a program in C to find the minimum length of a subarray such that sorting this subarray makes the whole array sorted.

Sample Solution:

C Code:

``````#include<stdio.h>

void findUnsortedSubArr (int arr1[], int arr_size)
{
int m = 0, en = arr_size-1, i, max, min;

for (m = 0; m < arr_size-1; m++)
{
if (arr1[m] > arr1[m+1])
break;
}
if (m == arr_size-1)
{
printf("The given array is sorted.");
return;
}

for(en = arr_size - 1; en > 0; en--)
{
if(arr1[en] < arr1[en-1])
break;
}

max = arr1[m]; min = arr1[m];
for(i = m + 1; i <= en; i++)
{
if(arr1[i] > max)
max = arr1[i];
if(arr1[i] < min)
min = arr1[i];
}

for( i = 0; i < m; i++)
{
if(arr1[i] > min)
{
m = i;
break;
}
}

for( i = arr_size -1; i >= en+1; i--)
{
if(arr1[i] < max)
{
en = i;
break;
}
}
printf("The minimum length of unsorted subarray which makes the given array sorted ");
printf("\nlies between the indeces %d and %d", m, en);
return;
}

int main()
{
int arr1[] = {10, 12, 15, 17, 28, 32, 42, 18, 56, 59, 67};
int arr_size = sizeof(arr1)/sizeof(arr1);
int i;
//------------- print original array ------------------
printf("The given array is:  \n");
for(i = 0; i < arr_size; i++)
{
printf("%d  ", arr1[i]);
}
printf("\n");
//-----------------------------------------------------------
findUnsortedSubArr(arr1, arr_size);
return 0;
}
```
```

Sample Output:

```The given array is:
10  12  15  17  28  32  42  18  56  59  67
The minimum length of unsorted subarray which makes the given array sorted
lies between the indeces 4 and 7
```

Pictorial Presentation: Flowchart: C Programming Code Editor:

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## C Programming: Tips of the Day

What does i = (i, ++i, 1) + 1; do?

In the expression (i, ++i, 1), the comma used is the comma operator

the comma operator (represented by the token ,) is a binary operator that evaluates its first operand and discards the result, and then evaluates the second operand and returns this value (and type).

Because it discards its first operand, it is generally only useful where the first operand has desirable side effects. If the side effect to the first operand does not takes place, then the compiler may generate warning about the expression with no effect.

So, in the above expression, the leftmost i will be evaluated and its value will be discarded. Then ++i will be evaluated and will increment i by 1 and again the value of the expression ++i will be discarded, but the side effect to i is permanent. Then 1 will be evaluated and the value of the expression will be 1.

It is equivalent to:

```i;          // Evaluate i and discard its value. This has no effect.
++i;        // Evaluate i and increment it by 1 and discard the value of expression ++i
i = 1 + 1;
```

Note that the above expression is perfectly valid and does not invoke undefined behavior because there is a sequence point between the evaluation of the left and right operands of the comma operator.

Ref : https://bit.ly/3saxONC

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