Question

complete the following c puzzles using the listed operators. no data control structures allowed (for, if, etc.)

/*

* logicalShift - shift x to the right by n, using a logic\

al shift

* Can assume that 0 <= n <= 31

* Examples: logicalShift(0x87654321,4) = 0x08765432

* Legal ops: ! ~ & ^ | + << >>

* Max ops: 20

* Rating: 3

*/

int logicalShift(int x, int n) {

}

/*

* bitCount - returns count of number of 1's in word

* Examples: bitCount(5) = 2, bitCount(7) = 3

* Legal ops: ! ~ & ^ | + << >>

* Max ops: 40

* Rating: 4

*/

int bitCount(int x) {

}

/*

* bang - Compute !x without using !

* Examples: bang(3) = 0, bang(0) = 1

* Legal ops: ~ & ^ | + << >>

* Max ops: 12

* Rating: 4

*/

int bang(int x) {

}

Answer 1

#include<stdio.h>
int logicalShift(int x, int n)
{
int mask = ~(-1 << n) << (32 - n);
return ~mask & ( (x >> n) | mask);
}

int bitCount(int x) {
   int count=0;

   while(x){
       count+= x&1;
       x>>=1;
   }
  
   return count;
}

int main(){
   int x = 0x87654321;
   x = logicalShift(x,4);
  
   printf("x=%x\n",x);
  
   printf("%d\n",bitCount(5) );
   printf("%d\n",bitCount(7) );
}