All numbers are present 3 times except one number which is there only once. Find that number.

#include<stdio.h>

int findUnique(int a[],int len){
int i,j;
int x=0;
int y;
int fact = 1;
for(i=0;i<32;i++){
y = 0;
for(j=0;j<len;j++){
y += a[j] & (1<<i);
}
x += fact * (y%3);
fact *= 2;
}
return x;
}

int main(){
int a[] = {1,2,3,2,3,4,3,1,1,2};
int n = findUnique(a,sizeof(a)/sizeof(a[0]));
printf("%d",n);
return 0;
}

Amazon 1st round Telephonic Interview

1) Tell me about yourself

2) How to tell if you a binary representation of a decimal unsigned number has all 1's ?

3) Given an integer array, randomize it.

4) In C++ when do you use virtual destructor ?

5) Loop through numbers from 1 to 100 and if the number is divisible by 3, print FIZZ , If it is divisible by 5, print BUZZ, If it is divisible by 15 print FIZZBUZZ and for all other numbers just print the number itself.

Finding if two numbers are of same sign or opposite sign without using arithmetic operators

#include<stdio.h>

int ifopposite(int a,int b){
return ((a^b) < 0)?1:0;
}

int main(){
int a=-5;
int b=6;
if(ifopposite(a,b)){
printf("numbers are of opposite sign");
} else {
printf("numbers are of same sign");
}
return 0;
}