Find the b-th bit for the number n on it's 64 bit representation with sign
Let n an integer and 0<=b<=63, b natural number. Find the b-th bit for the number n on it's 64 bit representation with sign.
and T be the number of test cases.
This is my attempt:
#include <iostream>
#define f cin
#define g cout
using namespace std;
int T;
long long n;
int b;
int main()
{
f >> T;
for(int i = 1; i <= T; ++i)
{
f >> n >> b;
int ans = 0;
bool ok = true;
while(n)
{
if(b == ans)
{
g << n % 2;
ok = false;
break;
}
n /= 2;
++ans;
}
if(ok) g << 0;
}
return 0;
}
but it does not work on all test cases... also is there another way to do this? or is there another way to store the bits? is there some special libraries? can you do this more efficiently with other tools? can you give me some information to read about bitmasks? and where and when you should use them and how are they usefull?
c++ bitmap bit-manipulation 64bit bit
asked Nov 11 at 18:02
C. Cristi
270116
add a comment |
Let n an integer and 0<=b<=63, b natural number. Find the b-th bit for the number n on it's 64 bit representation with sign.
and T be the number of test cases.
This is my attempt:
#include <iostream>
#define f cin
#define g cout
using namespace std;
int T;
long long n;
int b;
int main()
{
f >> T;
for(int i = 1; i <= T; ++i)
{
f >> n >> b;
int ans = 0;
bool ok = true;
while(n)
{
if(b == ans)
{
g << n % 2;
ok = false;
break;
}
n /= 2;
++ans;
}
if(ok) g << 0;
}
return 0;
}
but it does not work on all test cases... also is there another way to do this? or is there another way to store the bits? is there some special libraries? can you do this more efficiently with other tools? can you give me some information to read about bitmasks? and where and when you should use them and how are they usefull?
c++ bitmap bit-manipulation 64bit bit
asked Nov 11 at 18:02
C. Cristi
270116
What do you mean by sign? 2's complement representation?
– Mukul Gupta
Nov 11 at 20:25
add a comment |
Let n an integer and 0<=b<=63, b natural number. Find the b-th bit for the number n on it's 64 bit representation with sign.
and T be the number of test cases.
This is my attempt:
#include <iostream>
#define f cin
#define g cout
using namespace std;
int T;
long long n;
int b;
int main()
{
f >> T;
for(int i = 1; i <= T; ++i)
{
f >> n >> b;
int ans = 0;
bool ok = true;
while(n)
{
if(b == ans)
{
g << n % 2;
ok = false;
break;
}
n /= 2;
++ans;
}
if(ok) g << 0;
}
return 0;
}
but it does not work on all test cases... also is there another way to do this? or is there another way to store the bits? is there some special libraries? can you do this more efficiently with other tools? can you give me some information to read about bitmasks? and where and when you should use them and how are they usefull?
c++ bitmap bit-manipulation 64bit bit
asked Nov 11 at 18:02
C. Cristi
270116
Let n an integer and 0<=b<=63, b natural number. Find the b-th bit for the number n on it's 64 bit representation with sign.
and T be the number of test cases.
This is my attempt:
#include <iostream>
#define f cin
#define g cout
using namespace std;
int T;
long long n;
int b;
int main()
{
f >> T;
for(int i = 1; i <= T; ++i)
{
f >> n >> b;
int ans = 0;
bool ok = true;
while(n)
{
if(b == ans)
{
g << n % 2;
ok = false;
break;
}
n /= 2;
++ans;
}
if(ok) g << 0;
}
return 0;
}
but it does not work on all test cases... also is there another way to do this? or is there another way to store the bits? is there some special libraries? can you do this more efficiently with other tools? can you give me some information to read about bitmasks? and where and when you should use them and how are they usefull?
c++ bitmap bit-manipulation 64bit bit
c++ bitmap bit-manipulation 64bit bit
asked Nov 11 at 18:02
C. Cristi
270116
asked Nov 11 at 18:02
C. Cristi
270116
asked Nov 11 at 18:02
C. Cristi
270116
asked Nov 11 at 18:02
C. Cristi
270116
asked Nov 11 at 18:02
C. Cristi
270116
270116
What do you mean by sign? 2's complement representation?
– Mukul Gupta
Nov 11 at 20:25
add a comment |
What do you mean by sign? 2's complement representation?
– Mukul Gupta
Nov 11 at 20:25
What do you mean by sign? 2's complement representation?
– Mukul Gupta
Nov 11 at 20:25
What do you mean by sign? 2's complement representation?
– Mukul Gupta
Nov 11 at 20:25
add a comment |
1 Answer
1
active
oldest
votes
Computers already store the integers in its bitwise representation. All you need are bitwise operators to know a particular bit.
int bthbit(long long n, int b) {
if (n & (1ULL << b)) return 1;
return 0;
}
The solution uses bitwise & operator after left-shifting 1 by b bits. You may want to read about bitwise operators and bitmasks .
answered Nov 11 at 20:39
Mukul Gupta
1,02711230
A working example is ideone.com/v3ZWI1
– Mukul Gupta
Nov 11 at 20:42
add a comment |
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
Computers already store the integers in its bitwise representation. All you need are bitwise operators to know a particular bit.
int bthbit(long long n, int b) {
if (n & (1ULL << b)) return 1;
return 0;
}
The solution uses bitwise & operator after left-shifting 1 by b bits. You may want to read about bitwise operators and bitmasks .
answered Nov 11 at 20:39
Mukul Gupta
1,02711230
A working example is ideone.com/v3ZWI1
– Mukul Gupta
Nov 11 at 20:42
add a comment |
Computers already store the integers in its bitwise representation. All you need are bitwise operators to know a particular bit.
int bthbit(long long n, int b) {
if (n & (1ULL << b)) return 1;
return 0;
}
The solution uses bitwise & operator after left-shifting 1 by b bits. You may want to read about bitwise operators and bitmasks .
answered Nov 11 at 20:39
Mukul Gupta
1,02711230
A working example is ideone.com/v3ZWI1
– Mukul Gupta
Nov 11 at 20:42
add a comment |
Computers already store the integers in its bitwise representation. All you need are bitwise operators to know a particular bit.
int bthbit(long long n, int b) {
if (n & (1ULL << b)) return 1;
return 0;
}
The solution uses bitwise & operator after left-shifting 1 by b bits. You may want to read about bitwise operators and bitmasks .
answered Nov 11 at 20:39
Mukul Gupta
1,02711230
Computers already store the integers in its bitwise representation. All you need are bitwise operators to know a particular bit.
int bthbit(long long n, int b) {
if (n & (1ULL << b)) return 1;
return 0;
}
The solution uses bitwise & operator after left-shifting 1 by b bits. You may want to read about bitwise operators and bitmasks .
answered Nov 11 at 20:39
Mukul Gupta
1,02711230
answered Nov 11 at 20:39
Mukul Gupta
1,02711230
answered Nov 11 at 20:39
Mukul Gupta
1,02711230
answered Nov 11 at 20:39
Mukul Gupta
1,02711230
1,02711230
A working example is ideone.com/v3ZWI1
– Mukul Gupta
Nov 11 at 20:42
add a comment |
A working example is ideone.com/v3ZWI1
– Mukul Gupta
Nov 11 at 20:42
A working example is ideone.com/v3ZWI1
– Mukul Gupta
Nov 11 at 20:42
A working example is ideone.com/v3ZWI1
– Mukul Gupta
Nov 11 at 20:42
add a comment |
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What do you mean by sign? 2's complement representation?
– Mukul Gupta
Nov 11 at 20:25