NVIDIA Interview Question for Software Engineer Interns


Country: United States




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10
of 12 vote

Type pool[2] = {b, c};
	Type result = pool[ a == 0];

- Anonymous February 24, 2014 | Flag Reply
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-2
of 2 votes

int pool[2] = {b, c};
int index = ((uint32)0x80000000 & ((uint32)(b-c))) >> 31;
int result = pool[index];

- Anonymous February 24, 2014 | Flag
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0
of 0 votes

I can see that all the proposed solutions using conditional check internally. The programmer may not use it but but the compiler does unless we have a separate hardware so this operation differently. Please correct me in case i am wrong.

- soori October 07, 2014 | Flag
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6
of 8 vote

b*a + c*(1-a)

- Anonymous February 13, 2014 | Flag Reply
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0
of 0 votes

What if a is 2?

- Wade August 10, 2015 | Flag
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5
of 7 vote

This is solution for C++:

result = a * b + !a * c;

- roman.potapkin February 24, 2014 | Flag Reply
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10
of 10 votes

actually its result = !!a * b + !a * c;

- John smith May 28, 2014 | Flag
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0
of 0 votes

Awsome one.

- Vivek June 09, 2014 | Flag
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0
of 0 votes

All I could come up with was (a&(~b))^(a||c)
a == 0 ==> 0^c = c
a == 1 ==> ~b^1 = b
Your answer just blew my mind away

- Learn June 29, 2014 | Flag
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1
of 1 vote

Is this really correct? AFAIK any value not zero is true in C. A could be 2 and the result should be "b", but would it not be 2b here?

- Anonymous August 16, 2014 | Flag
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1
of 1 vote

a may not be 1, a can be any number except 0. then your result will be failed.

- utpal October 30, 2014 | Flag
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4
of 4 vote

int x = a&1;
int res = x*b + (1-x)*c;

- Puja February 12, 2014 | Flag Reply
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0
of 0 votes

nitpick: it shouldn't be a&1 but a != 0 // hopefully this is 1 in every relevant language. a might be 2, eg.

- JeffD February 16, 2014 | Flag
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4
of 6 vote

how about this:

a && (result = b, 1) || (result = c, 0)

- uuuouou February 24, 2014 | Flag Reply
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0
of 0 votes

Hi,

If its not much of a trouble. Can you please explain the logic behind this ?

- HakunaMatata April 06, 2014 | Flag
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0
of 0 votes

This is a clever answer!

I think a && (result = b, 1) || (result = c) should do though.

Explanation of the syntax:

Basic idea: (result = b, 1) always evaluates to "1". Just a clever way to set "result = b" while making sure the whole expression always evaluates to "1" even when value of b is 0.

Now the explanation is simple:
1. when a != 0, only (result = b, 1) gets executed effectively setting result to b.
2. when a == 0, no matter what, (result = b, 1) and (result = c, 0) gets evaluated in that order effectively setting result to c.

- karuthedam July 01, 2014 | Flag
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0
of 0 votes

It's a good explanation. I am not it is perfectly complete, though. There is one property here that is necessary for it to work that is not mentioned and that is the short-circuiting of the disjunctive boolean operator when one of its operand predicates has evaluated to a true value. If that was not the case, the first part before the || operator could evaluate to true and "result" still be assigned to "c".

As to why (result = b, 1) always evaluates to "1", it is due to a sequence of statements always returning the value of the last expression.

BTW, I haven't put much thought into this, yet, but I am not sure this would work in more strongly typed languages like C# and the question does not ask about C/C++ specifically. I'll think about that a bit more.

- The Internet August 17, 2014 | Flag
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0
of 0 votes

s/I am not it is perfectly complete/I am not sure it is perfectly complete/m

- The Internet August 17, 2014 | Flag
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2
of 2 vote

result = ((!(!a)) * b) + ((!a) * c);
since a can be any non-zero value !!!

- Santa March 18, 2014 | Flag Reply
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0
of 0 votes

Yeah, I was thinking that, too. Good catch! It's also better that you put parentheses around each operand, because it would then work for any integer-valued expression.

- The Internet August 17, 2014 | Flag
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0
of 0 votes

Err ... strike the part about the integer-valued expression. It has nothing to do with being integer-valued, nor should it.

- The Internet August 17, 2014 | Flag
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0
of 0 vote

Assume b and c are integers:

int[] array = new int[2];
int[0] = b;
int[1] = c;

result = array[a];

- Michael.J.Keating February 12, 2014 | Flag Reply
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0
of 0 votes

in C get false only if a is 0. True for +ive and -ive a's so my correction to this (based on the trick used in an answer above_
int[] array = new int[2];
int[0] = c;
int[1] = b;

result = array[!a];

- Satish July 02, 2015 | Flag
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0
of 0 vote

Find a way to turn non-zero value of a into an all-ones bit pattern using only bitwise operators.

a |= a >> 1; a |= a >> 2; a |= a >> 4; a |= a >> 8; a |= a >> 16;
a |= a << 1; a |= a << 2; a |= a << 4; a |= a << 8; a |= a << 16;

result = (a & b) | (~a & c)

- nivi1991 February 12, 2014 | Flag Reply
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0
of 0 vote

above code works for binary values of a..here is more general solution
int t= (a-1)<0;
int result = (1-t)*b + t*c;

- Puja February 12, 2014 | Flag Reply
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0
of 0 vote

result = b+c - a*c + (a-1)*b

- Anonymous February 13, 2014 | Flag Reply
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0
of 0 votes

result= a*b + (1-a)*c
Simple !!!!!!!

- vikash February 16, 2014 | Flag
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0
of 0 votes

int main()
{
int v,result;
int a,b,c;
scanf("%d",&a);
v=if(a)
result=v*b+(1-v)*c;
printf("%d",result);
}

- navam May 06, 2020 | Flag
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0
of 0 votes

int v,result;
int a,b,c;
scanf("%d",&a);
v=if(a)
result=v*b+(1-v)*c;
printf("%d",result);

- navam May 06, 2020 | Flag
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0
of 0 vote
In case of java where boolean false does not mean 0 and true doesnot mean any number Where true mean true and false mean false.Following code can be implemented {{{ static int assign(Boolean b,int a ,int c) { String str=b.toString(); char[] x=str.toCharArray(); try { char j=x[4]; return c; } catch(Exception ex) { return a; } } }} } - Abhishek Kumar February 14, 2014 | Flag Reply
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0
of 0 vote

static int assign(Boolean b,int a ,int c)
{
String str=b.toString();
char[] x=str.toCharArray();
try
{
char j=x[4];
return c;
}
catch(Exception ex)
{
return a;
}

}

- Abhishek Kumar February 14, 2014 | Flag Reply
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0
of 0 vote

int max_with_no_conditionals(int a, int b, int c)
{
    int arr[] = { c, b };
    return arr[!!a]; // force boolean (0 or 1) conversion
}

- Using an array makes things easier February 15, 2014 | Flag Reply
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0
of 0 votes

wow this is a nice answer.

- aka February 16, 2014 | Flag
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0
of 0 votes

Hey please tell me how compiler does !!a without conditional operation

soori

- Anonymous April 07, 2014 | Flag
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0
of 0 vote

~(a - 1) & b | (a - 1) & c

- donkey code February 17, 2014 | Flag Reply
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0
of 0 votes

Forgot to force boolean:

~(!!a - 1) & b | (!!a - 1) & c

- donkey code February 17, 2014 | Flag
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0
of 0 vote

:)

- Anonymous February 17, 2014 | Flag Reply
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0
of 0 vote

unsigned int r = c^((b^c) & -(a));

- Anonymous February 22, 2014 | Flag Reply
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0
of 0 vote

res = b*(!!a) + c*(!a);

- Anonymous February 23, 2014 | Flag Reply
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0
of 0 vote

What happens if you use a switch? is if valid?

switch(a)
case a:
return b;

default:
return c;

- Anonymous February 24, 2014 | Flag Reply
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1
of 1 vote

switch is condition operator

- roman.potapkin February 25, 2014 | Flag
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0
of 0 votes

switch is a conditional statement not condition operator

- v.krishna1708 April 23, 2014 | Flag
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0
of 0 votes

Hey Dude!!!!
switch is also conditional statement.

- Anonymous January 06, 2015 | Flag
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0
of 0 vote

d = !a;
result = ((!d)*(b)) + ((d)*(c));

- dreamer February 27, 2014 | Flag Reply
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0
of 0 votes

if a is true i.e 1 then it returns b else it returns c

- sai krishna June 07, 2014 | Flag
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0
of 0 vote

result = (!!a)*b + (1-!!a)*c;

- Anonymous March 02, 2014 | Flag Reply
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0
of 0 vote

How about following?
c^((b^c)&-(a&1))
Following is logic behind this.
1. First mask a to convert into either 1 or 0 using a&1
2. Now change (a&1) into negative number, in case of 1 it will be converted into -1 and in case of 0 it will be 0. When it will become -1 then in binary it will be full of 1 sequence.
3. Following are two cases.
a. When a&1 is 0 then result should be c
b. When 1&1 is 1 then result should be b.
Based on above two condition applied logic.

- dilip.kumar2k6 April 04, 2014 | Flag Reply
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0
of 0 vote

int a

return b=a||1;
return c=a&&0;

- Anonymous April 11, 2014 | Flag Reply
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0
of 2 vote

while(a) {
result = b;
return;
}
result = c
is it correct?

- Faiz Halde April 16, 2014 | Flag Reply
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0
of 0 votes

It is correct if you do not view the loop condition of while as a conditional statement. However, then a lot of the other suggested solutions, such as the ones based on boolean expressions, may also be incorrect.

- The Internet August 17, 2014 | Flag
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0
of 0 vote

r = y ^ ((x ^ y) & -(x < y));
Why it works:

C represents the Booleans
TRUE
and
FALSE
with
the integers
1
and
0
, respectively.

If
x < y
, then
−(x < y) = −1
, which is all
1
’s in
two’s complement representation. Therefore,
we have
y ^ (x ^ y ) = x
.

If
x ≥ y
, then
−(x < y) = 0
. Therefore, we have
y ^ 0 = y
.

- Anonymous May 09, 2014 | Flag Reply
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0
of 0 vote

Assuming all functions return

uint8_t

, how about:

uint8_t result = 0xFF;
(result & ((((a()) ^ 0) & (b())) | ((!((a())) ^ 0) & (c()))))

- DVS June 19, 2014 | Flag Reply
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0
of 0 votes

Small change to the solution.

a()

returns 0 or 1.

uint8_t result = 0xFF;
result = (result & ((((a()) ^ 0) & (b())) | ((!(((a())) ^ 0)) & (c()))))

/*--------------------------------------------------*/

Explanation:

Let

switch = a ^ 0;

So,

result = result & [(switch & b) | (!switch & c)]

- DVS June 19, 2014 | Flag
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0
of 0 vote

int max(int a, int b, int c)
{
int m = a;
(m < b) && (m = b); //these are not conditional statements.
(m < c) && (m = c); //these are just boolean expressions.
return m;
}

- kevytosh July 15, 2014 | Flag Reply
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0
of 0 vote

result=((a && 1)*(b-c))+c

- VinothKumar July 15, 2014 | Flag Reply
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0
of 0 vote

I used no conditional operators( >, < , ==) for my solution.

a = a*a+1; 
int *array = new int[a];
array[a-1] = b;
array[0] = c;
result = array[a-1];

If the variable a was 0, then the length of the array is 1 and a-1 equals 0.
Therefore the variable c in array[0] = c overrides b in array[a-1] = b

- Amit S July 17, 2014 | Flag Reply
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0
of 0 vote

if(a){
return b;
}
else{
return c;
}


is it right...????

- kamal August 15, 2014 | Flag Reply
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0
of 0 votes

question says "without using conditional statements"..

- Hari October 03, 2014 | Flag
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0
of 0 vote

result = (a!=0)*b + (a==0)*c;

- Anonymous August 21, 2014 | Flag Reply
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0
of 0 vote

If result, a, b and c are (, or can be broken into ) integral type then the simple solution using bitwise operator would be

result = (b & ~((!!a)-1)) | (c & ((!!a)-1));

- Toseef September 01, 2014 | Flag Reply
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0
of 0 vote

/* key is to convert a = 1 if a!=0 and a =0 otherwise with out using condition - http://bits.stephan-brumme.com/sign.html */
// ((unsigned int) a) >> 31) will be 0x00000001 for negative numbers, else 0x00000000

// negateA >> 31 will be 0x00000001 for positive numbers, else 0x00000000
unsigned int negateA = (unsigned int) -a;

a = (int)((negateA >> 31) | ((unsigned int) a) >> 31));

a = (a * c) + b - (a * b);

- naveedsm September 16, 2014 | Flag Reply
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0
of 0 vote

since we need a alternative to element1==element2 , then
hashcode(elemet1) - hascode(element2) !=0{
//logic
}

- Anonymous October 30, 2014 | Flag Reply
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0
of 0 vote

c ^ ( (b ^ c) & -(a) )

- Skor November 05, 2014 | Flag Reply
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0
of 0 vote

<script type="text/javascript">
var a = false ;	
result = nocondition(a);
console.log(result);
function nocondition(a){
var b=1;
var c=2;
	 while(a){
		return b;
	 }
 return c;
 }

</script>

Though above code is written and tested in javascript which works. Similar construct is available in c. So this can be one of several solutions.

- Bhishma January 22, 2015 | Flag Reply
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0
of 0 vote

Use xor to flip the bit

unsigned int ternary(unsigned int a, unsigned int b, unsigned int c)
{
    unsigned int q = 1 ^ a; //flip the bit
    return a * b + q * c;
}

- xmatrix February 04, 2015 | Flag Reply
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0
of 0 vote

Well in JavaScript it would be
x = (a && b) || c ;

- Saikat Guha April 30, 2015 | Flag Reply
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0
of 0 vote

output = xnor(result , a)*b + xor(result,a)*c

- linliz May 25, 2015 | Flag Reply
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0
of 0 vote

output = xnor(result,a)*b + xor(result,b) * c

- linliz May 25, 2015 | Flag Reply
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0
of 0 vote

result=b*(a^0)+c*(a^1)

- competitivecoder June 05, 2015 | Flag Reply
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0
of 0 vote

unsigned compute(int a, int b, int c)
{
    int mask = ~(int)(bool(a)) + 1;

    unsigned result = (mask & b) + (~mask & c);

    return result;
}

- NB June 19, 2015 | Flag Reply
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0
of 0 vote

#include<iostream>
using namespace std;

int main()
{
    int a, b, c;
    
    cout<<"  Enter a, b, c :- ";
    cin>>a>>b>>c;

    int result = (a&&0xFFFFFFFF)*b + !(a&&0xFFFFFFFF)*c;    //result = a?b:c;
    cout<<"  Result = "<<result<<endl;
    
    system("PAUSE");
    return 0;
}

- skum June 23, 2015 | Flag Reply
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0
of 0 votes

correction for above code :-
result = (a&&1)*b + !(a&&1)*c; //result = a?b:c;

- skum June 23, 2015 | Flag
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0
of 0 votes

correction for above code :-
int result = (a&&1)*b + !(a&&1)*c; //result = a?b:c;

- skum June 23, 2015 | Flag
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0
of 0 vote

here is my solution that does not use any conditional operands, it just uses a hashtable consisting of 2 values. I am assuming that if a is false, a = 0x0. therefore

void* conditionLessComparison(int conditionA, void* resultTrue, void* resultFalse){
	int result;
	void*[] toReturn = {resultFalse, resultTrue};

	return toReturn[conditionA%1];

}

basically if a is false, it will be 0x0, 0x0 % 1 = 0, if a is anything else, % 1 will be 1

- Ethan July 04, 2015 | Flag Reply
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0
of 0 vote

a & b || c

- candy August 21, 2015 | Flag Reply
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0
of 0 vote

a & b || c

- candy August 21, 2015 | Flag Reply
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0
of 0 vote

r=(((a*b)|(!a*c))/(a|!a));

- voc_faps September 16, 2015 | Flag Reply
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0
of 0 vote

r=(((a*b)|(!a*c))/(a|!a));

- voc_faps September 16, 2015 | Flag Reply
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0
of 0 vote

what is a, b, c are expressions?

while(a) {
b;
break
}

while(!a) {
c;
break;
}

- Anonymous November 11, 2016 | Flag Reply
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0
of 0 vote

result = b;
(a * c) && (result = c);
return result;

This should work.

- murali.bheemineni July 18, 2017 | Flag Reply
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0
of 0 vote

1 #include<stdio.h>
  2 
  3 int implement_ternary_operator(int a,int b,int c)
  4 
  5 {
  6 
  7     return ((!!a)*b + (!a)*c);
  8 
  9 }
 10 
 11 int main()
 12 
 13 {
 14 
 15     int a = 1,b =10,c =20;
 16 
 17     printf(" result = %d\n",implement_ternary_operator(a,b,c));
 18 
 19     a=0;
 20 
 21 
 22     printf(" result = %d",implement_ternary_operator(a,b,c));
 23 
 24 }

- sandeepkumar211221 August 16, 2017 | Flag Reply
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0
of 0 vote

1 #include<stdio.h>
  2 
  3 int implement_ternary_operator(int a,int b,int c)
  4 
  5 {
  6 
  7     return ((!!a)*b + (!a)*c);
  8 
  9 }
 10 
 11 int main()
 12 
 13 {
 14 
 15     int a = 1,b =10,c =20;
 16 
 17     printf(" result = %d\n",implement_ternary_operator(a,b,c));
 18 
 19     a=0;
 20 
 21 
 22     printf(" result = %d",implement_ternary_operator(a,b,c));
 23 
 24 }

- sandeepkumar211221 August 16, 2017 | Flag Reply
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0
of 0 vote

for c++
result = bool(a-b);

- dark_nite77 November 25, 2017 | Flag Reply
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-1
of 1 vote

if (a == true)
	result = b;
else
	result = c;

- Anonymous February 12, 2014 | Flag Reply
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0
of 0 votes

Isn't these are conditional statement?

- guruNotCoding February 12, 2014 | Flag
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0
of 0 votes

Hey you are using if and else which are conditional statements

- Abhishek Kumar February 14, 2014 | Flag
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-1
of 1 vote

The question clearly says, we shouldn't use Conditional statement.

#include <stdio.h>
int main()
{
int b = 3, c = 4;
int pool_values[2] = {c, b};
int a1 = 0, a2 = 5;
int result = 0;
result = pool_values[(a1 > 0)];
printf("result = %d\n", result);
result = pool_values[(a2 > 0)];
printf("result = %d\n", result);
return 0;
}
And the output will be:
result = 4
result = 3

- Venkat March 06, 2014 | Flag Reply
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-1
of 1 vote

little addition to roman's code above
int iDecide(int a,int b,int c)
{
a=!a;
a=!a;
return ((a*b) + (!a *c));

- Anonymous March 09, 2014 | Flag Reply
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-1
of 3 vote

int iDecide(int a,int b,int c)
{
//Following to make sure the multiplication factor is made to 1 or 0
a=!a;
a=!a;
return ((a*b) + (!a *c));
}

- Anonymous March 09, 2014 | Flag Reply
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-1
of 1 vote

result = (a * b) + ((!a) * c);
result = result /a;

- LoNa March 17, 2014 | Flag Reply
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1
of 1 vote

This will return undefined value if a = 0

- Ganesh March 29, 2014 | Flag


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