给定一个非负数n和两个值l和r 。问题是检查在n的二进制表示形式中的l到r范围内,所有位是否都未设置。这些位从右到左编号,即,最低有效位被认为在第一位置。
约束: 1 <= l <= r <= n的二进制表示形式的位数。
例子:
Input : n = 17, l = 2, r = 4
Output : Yes
(17)10 = (10001)2
The bits in the range 2 to 4 are all unset.
Input : n = 39, l = 4, r = 6
Output : No
(39)10 = (100111)2
The bits in the range 4 to 6 are all not unset.
方法:以下是步骤:
- 计算num =(((1 << r)– 1)^((1 <<(l-1))– 1)。这将产生一个数字num,它具有r个位数,并且范围l至r的位数是唯一的设置位。
- 计算new_num = n&num。
- 如果new_num == 0,则返回“是”(在给定范围内所有位均未设置)。
- 否则返回“ No”(在给定范围内所有位均未设置)。
C++
// C++ implementation to check whether all the bits
// are unset in the given range or not
#include
using namespace std;
// function to check whether all the bits
// are unset in the given range or not
bool allBitsSetInTheGivenRange(unsigned int n,
unsigned int l, unsigned int r)
{
// calculating a number 'num' having 'r'
// number of bits and bits in the range l
// to r are the only set bits
int num = ((1 << r) - 1) ^ ((1 << (l - 1)) - 1);
// new number which could only have one or more
// set bits in the range l to r and nowhere else
int new_num = n & num;
// if true, then all bits are unset
// in the given range
if (new_num == 0)
return true;
// else all bits are not unset
// in the given range
return false;
}
// Driver program to test above
int main()
{
unsigned int n = 17;
unsigned int l = 2, r = 4;
if (allBitsSetInTheGivenRange(n, l, r))
cout << "Yes";
else
cout << "No";
return 0;
}
Java
// Java implementation to check
// whether all the bits are
// unset in the given range or not
class GFG
{
// function to check whether
// all the bits are unset in
// the given range or not
static boolean allBitsSetInTheGivenRange(int n,
int l,
int r)
{
// calculating a number 'num'
// having 'r' number of bits
// and bits in the range l
// to r are the only set bits
int num = ((1 << r) - 1) ^
((1 << (l - 1)) - 1);
// new number which could only
// have one or more set bits in
// the range l to r and nowhere else
int new_num = n & num;
// if true, then all bits are
// unset in the given range
if (new_num == 0)
return true;
// else all bits are not
// unset in the given range
return false;
}
// Driver Code
public static void main(String[] args)
{
int n = 17;
int l = 2, r = 4;
if (allBitsSetInTheGivenRange(n, l, r))
System.out.println("Yes");
else
System.out.println("No");
}
}
// This code is contributed
// by Smitha
Python3
# Python3 implementation to
# check whether all the bits
# are unset in the given
# range or not
# function to check whether
# all the bits are unset in
# the given range or not
def allBitsSetInTheGivenRange(n, l, r):
# calculating a number 'num'
# having 'r' number of bits
# and bits in the range l
# to r are the only set bits
num = (((1 << r) - 1) ^
((1 << (l - 1)) - 1))
# new number which could only
# have one or more set bits in
# the range l to r and nowhere else
new_num = n & num
# if true, then all bits are
# unset in the given range
if (new_num == 0):
return True
# else all bits are not
# unset in the given range
return false
# Driver Code
n = 17
l = 2
r = 4
if (allBitsSetInTheGivenRange(n, l, r)):
print("Yes")
else:
print("No")
# This code is contributed
# by Smitha
C#
// C# implementation to check
// whether all the bits are
// unset in the given range or not
using System;
class GFG
{
// function to check whether
// all the bits are unset in
// the given range or not
static bool allBitsSetInTheGivenRange(int n,
int l,
int r)
{
// calculating a number 'num'
// having 'r' number of bits
// and bits in the range l
// to r are the only set bits
int num = ((1 << r) - 1) ^
((1 << (l - 1)) - 1);
// new number which could
// only have one or more
// set bits in the range
// l to r and nowhere else
int new_num = n & num;
// if true, then all
// bits are unset
// in the given range
if (new_num == 0)
return true;
// else all bits are not
// unset in the given range
return false;
}
// Driver Code
public static void Main()
{
int n = 17;
int l = 2, r = 4;
if (allBitsSetInTheGivenRange(n, l, r))
Console.Write("Yes");
else
Console.Write("No");
}
}
// This code is contributed
// by Smitha
PHP
Javascript
输出:
Yes