second largest element in an array

[Rajesh]

Hello Everybody,

Can anybody help me to write a C program for finding the second largest
element in an array.

without using any sort algo. The array may conatin duplicate elements.
The algo should run in O(n) time.

Rajesh

 

[Nudge]

Can anybody help me to write a C program for finding the second
largest element in an array without using any sort algo. The
array may contain duplicate elements. The algo should run in O(n)
time.

Again, show us what you've come up with so far.

 

[maraguida]

Please define "second largest element in an array".
For the following arrays which is the second largest element?

a) int x[] = {1};
b) int x[] = {2, 2};
c) int x[] = {4, 4, 8, 8};

The answer to b) is x[0] or x[1]?

 

[Rajesh]

Answer to a) should be max1=1 and max2=1
Answer to b) should be max1=2 and max2=2
Answer to c) should be max1=8 and max2=4

 

[Mark McIntyre]

Hello Everybody,

Can anybody help me to write a C program for finding the second largest
element in an array.

Homework problem.

without using any sort algo. The array may conatin duplicate elements.

Show us your attempt so far.

The algo should run in O(n) time.

If you have problems with the algo, you shold ask in comp.programming
first.

I'd do this thusly by the way

system( sprintf (mstr,
"sort -n -u %s | tail -2 | head -1 > result.txt",
file_of_data);



Mark McIntyre

 

[Rajesh]

max1 = max2 = a[0];

for(i = 1; i< n; i++)
{
if(a > max1)
{
max2 = max1;
max1 = a;
}
else if((a > max2 && a < max1) || max1==max2)
{
max2 = a;
}
}

max1 will contain the largest element and max2 will contain the second
largest element

 

[Mara Guida]

max1 = max2 = a[0];

for(i = 1; i< n; i++)
{
if(a > max1)
{
max2 = max1;
max1 = a;
}
else if((a > max2 && a < max1) || max1==max2)
{
max2 = a;
}
}

max1 will contain the largest element and max2 will contain the second
largest element

After I completed your program (#include, int main(void), printf(),
....) and corrected the errors in it, it executed according to the
specifications.

 

[Scorpio]

max1 = max2 = a[0];

for(i = 1; i< n; i++)
{
if(a > max1)
{
max2 = max1;
max1 = a;
}
else if((a > max2 && a < max1) || max1==max2)

silly.
The condition "&& a < max1) || max1==max2" is not required.

{
max2 = a;

ITYM a;

}
}

max1 will contain the largest element and max2 will contain the second
largest element

You seem to be trying to quiz/test others here.
If you need any help in solving a problem, show your attempt and
c.l.c will help you solve it.


Sharath A.V

 

[CBFalconer]

Can anybody help me to write a C program for finding the second
largest element in an array. without using any sort algo. The
array may conatin duplicate elements. The algo should run in O(n)
time.

Yes, we can. However we charge 200 USD per hour for doing
homework, with payment in advance for at least 4 hours effort. If
you supply the name and email of your instructor so that we can
submit your homework directly we will cut the price to 100 USD per
hour.

If you fail to properly quote context in any replies, the price is
doubled.

--
"If you want to post a followup via groups.google.com, don't use
the broken "Reply" link at the bottom of the article. Click on
"show options" at the top of the article, then click on the
"Reply" at the bottom of the article headers." - Keith Thompson
More details at: <http://cfaj.freeshell.org/google/>

 

[Martin Ambuhl]

Please define "second largest element in an array".
For the following arrays which is the second largest element?

a) int x[] = {1};
b) int x[] = {2, 2};
c) int x[] = {4, 4, 8, 8};

The answer to b) is x[0] or x[1]?

Yes. The phrase "second largest element in an array" is not sufficient
to specify which of two equal elements is the "second largest."

Nor is it necessarily true that the answer to (c) is x[2] or x[3]; some
readings of "second largest element" would require the answer to (c) to
be x[0] or x[1].

 

[tedu]

system( sprintf (mstr,
"sort -n -u %s | tail -2 | head -1 > result.txt",
file_of_data);

converting sprintf's return to a char * is unlikely to work correctly
on most systems.

 

[Mark McIntyre]

converting sprintf's return to a char * is unlikely to work correctly
on most systems.

I agree, but then a) the entire answer was almost certainly not what
the OP wanted and b) if we posted 100% accurate code in response to
homework questions, nobody would ever learn.


Mark McIntyre

 

[Flash Gordon]

I agree, but then a) the entire answer was almost certainly not what
the OP wanted and b) if we posted 100% accurate code in response to
homework questions, nobody would ever learn.

You forgot c) on the Psychic Station 200 undefined behaviour does what
the user wants, so on the PS200 it will give the OP the largest two
elements

 

[Thad Smith]

max1 = max2 = a[0];

for(i = 1; i< n; i++)
{
if(a > max1)
{
max2 = max1;
max1 = a;
}
else if((a > max2 && a < max1) || max1==max2)
{
max2 = a;
}
}

max1 will contain the largest element and max2 will contain the second
largest element

Really? Try a[] = {5,4,3};

 

[Thad Smith]

Please define "second largest element in an array".
For the following arrays which is the second largest element?

a) int x[] = {1};
b) int x[] = {2, 2};
c) int x[] = {4, 4, 8, 8};

The answer to b) is x[0] or x[1]?

The answer to second largest is
a) none
b) none
c) 4.

 

[Lemor]

here's your porgram:

I compile my prorams in VC++. it'll surely work!

#include<iostream>

using namespace std;

int main()
{
int aray[100],n,temp=0,m;
cin>>n;

for(int j=0;j<n;j++)
{
cin>>aray[j];
}
for(j=0;j<n;j++)
{
if(aray[j] >= temp)
{
temp=aray[j];
m=j;
}
}
aray[m]=0;temp=0;

for(j=0;j<n;j++)
{
if(aray[j] >= temp)
{
temp=aray[j];
}
}
cout<<endl<<temp;
return 0;
}

 

[Lemor]

#include<iostream>

using namespace std;

int main()
{
int aray[100],n,temp=0,m;
cin>>n;

for(int j=0;j<n;j++)
{
cin>>aray[j];
}
for(j=0;j<n;j++)
{
if(aray[j] >= temp)
{
temp=aray[j];
m=j;
}
}
aray[m]=0;temp=0;

for(j=0;j<n;j++)
{
if(aray[j] >= temp)
{
temp=aray[j];
}
}
cout<<endl<<temp;
return 0;
}

 

[Lemor]

second largest element is the the second largest value in a given
array.

int x[] = {2, 2};

Both of then are largest numbers in the array given as both are same.
No one of them is second largest.

 

[Martin Ambuhl]

#include<iostream>

[and more obscurantist crap]

If you want C++, go to < Just in case you're one of
those that posts C++-looking code and the does a stuck-pig "That's not
C++, it's <useless language name here>", whatever the hell your crap
was, it's off-topic and should be kept to yourself.

 

[Martin Ambuhl]

here's your porgram:

I compile my prorams in VC++. it'll surely work!

#include<iostream>

More C++? Please go away. If you don't know the difference between C
and C++, you surely have no business offering "advice."