# 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.
Submitted by Radib Kar, on December 05, 2018

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

Example: Type1: (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: Type2: (second minimum doesn’t exist as size of array < 2)

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

Output:
no second minimum
```

Example: Type3: (all elements are same, thus only one minimum element)

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

Output:
no second minimum
```

Algorithm:

1. Define two variable min & sec_min
2. Initialize min to array & 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 implementation to 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;

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

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
```

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