# C program to find two largest elements in a one dimensional array

Here, we are implementing a C program that finds the two largest numbers from a one dimensional array.
Submitted by Radib Kar, on December 05, 2018

Problem statement: Write a C program to find two largest elements 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 43

Output:
54 43

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

Input:
Array size : 1
Elements: 4

Output:
4

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

Input:
Array size : 4
Elements: 12 12 12 12

Output:
12

Algorithm:

1. Define two variable max & sec_max
2. Initialize max to array[0] & sec_max to INT_MIN
3. Scan the entire array
4. a. For(int i=0;i<n;i++)
if array[i]>max
then update max to array[i]&sec_max to previous max value
else if array[i] is greater than sec_max but less than max
then update sec_max to array value
do nothing to max
End for loop

5. If still sec_max has the value INT_MIN
Only one largest value exists, print it
Else
Print max & sec_max

## C implementation to find two largest elements in a one dimensional array

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

void findTwoMax(int* a,int n){
int max=a[0]; //initialize max to first array element
int sec_max=INT_MIN,temp=0; //initialize max to first array element

for(int i=0;i<n;i++){ //scan the entire array
//if a[i]> max then update max to array value &
//second max to previous max value
if(a[i]>max){
sec_max=max;
max=a[i];
}
//else if a[i] is greater than second max but less
//than max then update second max to array value
else if (a[i] > sec_max && a[i] < max)
sec_max=a[i];
//do nothing to max
}
//if second max is still at its initialized value
//then no second maximum exists at all
if(sec_max==INT_MIN)
printf("only one large element: %d ",max);
else
printf("First largest element: %d  & second largest element : %d",max,sec_max);
}

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

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

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

//find two largest no
findTwoMax(a,n);

return 0;
}

Output

First run:
enter no of elements
4
enter the elements........
32 54 -6 43
First largest element: 54  & second largest element : 43

Second run:
enter no of elements
1
enter the elements........
4
only one large element: 4

Third run:
enter no of elements
4
enter the elements........
12 12 12 12
only one large element: 12