# C program to find second smallest element in a one dimensional array

Here, we are implementing a C program that will read a one dimensional array of integers and find the second smallest element it. By Radib Kar, on December 05, 2018

## Problem statement

Write a C program to find the second smallest element in a one dimensional array.

## Examples

Example: Type 1: (all the elements are not same & no of element is more than two)

```Input:
Array size: 4
Elements: 32 54 -6 -15

Output:
-6
```

Example: Type 2: (second minimum doesn’t exist as size of array < 2)

```Input:
Array size : 1
Elements: 4

Output:
no second minimum
```

Example: Type 3: (all elements are same, thus only one minimum element)

```Input:
Array size : 4
Elements: 3 3 3 3

Output:
no second minimum
```

## Algorithm to find second smallest element in a one dimensional array

1. Define two variable min & sec_min
2. Initialize min to array[0] & sec_min to INT_MAX
3. Scan the entire array
4. ```a. for(int i=0;i<n;i++)
if array[i]<min
then update min to array[i]&sec_min to previous min value
else if array[i] is smaller than sec_min but greater than min
then update sec_min to array value
do nothing to min
End for loop
```
5. If still sec_min has the value INT_MAX
Only one minimum value exists, print "No second minimum value exists"
Else
Print sec_min

## C program to find second smallest element in a one dimensional array

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

int findSecondMin(int * a, int n) {
if (n <= 1)
return 0;

//initialize max to first array element
int min = a[0];
//initialize min to first array element
int sec_min = INT_MAX, temp = 0;

for (int i = 0; i < n; i++) { //scan the entire array
//if a[i]< min then update min to array value
//& second min to previous min value
if (a[i] < min) {
sec_min = min;
min = a[i];
}
//else if a[i] is smaller than second min but greater
//than min then update second min to array element value
else if (a[i] < sec_min && a[i] > min)
sec_min = a[i];
}
//if sec_min is still at its initialized value
//then no second minimum exists at all
if (sec_min == INT_MAX)
return 0;
//else return second maximum
return sec_min;
}

int main() {
int n, sec_min = 0;

printf("enter no of elements\n");
scanf("%d", & n);

//dynamic array created
int * a = (int * ) malloc(sizeof(int) * n);

printf("enter the elements........\n");
//taking input
for (int i = 0; i < n; i++)
scanf("%d", & a[i]);

//find second maximum value
sec_min = findSecondMin(a, n);

if (sec_min == 0) //if no second minimum exists
printf("no second minimum exists\n");
else
printf("The second minimum no is : %d\n", sec_min);

return 0;
}
```

### Output

```First run:
enter no of elements
4
enter the elements........
32 54 -6 -15
The second minimum no is : -6

Second run:
enter no of elements
1
enter the elements........
4
no second minimum exists

Third run:
enter no of elements
4
enter the elements........
3
3
3
3
no second minimum exists
```

To understand the above program, you should have the basic knowledge of the following C language topics: