给定一个二进制数作为字符串,打印其2的补码。
二进制数的2的补码为1,再加上二进制数的1的补码。请注意,1的补码只是给定二进制数的翻转。
例子:
2's complement of "0111" is "1001"
2's complement of "1100" is "0100"
我们强烈建议您单击此处并进行实践,然后再继续解决方案。
我们在下面的文章中讨论了1和2的补码。
二进制数的1和2的补码。
上面讨论的方法遍历二进制字符串两次以找到2的补码,首先找到1的补码,然后使用1的补码找到2的补码
在这篇文章中,讨论了有效的2补码方法,该方法仅遍历字符串一次。我们从最后开始遍历字符串,直到没有遍历单个1,然后翻转所有字符串值,即0到1和1到0。
注:这里如果1没有在字符串中只追加1字符串的开始存在,那么处理极端情况即。
插图 :
Input: str = "1000100"
Output: 0111100
Explanation: Starts traversing the string from last,
we got first '1' at index 4 then just flip the bits
of 0 to 3 indexes to make the 2's complement.
Input: str = "0000"
Output: 10000
Explanation: As there is no 1 in the string so just
append '1' at starting.
C++
// An efficient C++ program to find 2's complement
#include
using namespace std;
// Function to find two's complement
string findTwoscomplement(string str)
{
int n = str.length();
// Traverse the string to get first '1' from
// the last of string
int i;
for (i = n-1 ; i >= 0 ; i--)
if (str[i] == '1')
break;
// If there exists no '1' concatenate 1 at the
// starting of string
if (i == -1)
return '1' + str;
// Continue traversal after the position of
// first '1'
for (int k = i-1 ; k >= 0; k--)
{
//Just flip the values
if (str[k] == '1')
str[k] = '0';
else
str[k] = '1';
}
// return the modified string
return str;;
}
// Driver code
int main()
{
string str = "00000101";
cout << findTwoscomplement(str);
return 0;
}
Java
// An efficient Java program to find 2's complement
class Test
{
// Method to find two's complement
static String findTwoscomplement(StringBuffer str)
{
int n = str.length();
// Traverse the string to get first '1' from
// the last of string
int i;
for (i = n-1 ; i >= 0 ; i--)
if (str.charAt(i) == '1')
break;
// If there exists no '1' concat 1 at the
// starting of string
if (i == -1)
return "1" + str;
// Continue traversal after the position of
// first '1'
for (int k = i-1 ; k >= 0; k--)
{
//Just flip the values
if (str.charAt(k) == '1')
str.replace(k, k+1, "0");
else
str.replace(k, k+1, "1");
}
// return the modified string
return str.toString();
}
// Driver method
public static void main(String[] args)
{
StringBuffer str = new StringBuffer("00000101");
System.out.println(findTwoscomplement(str));
}
}
Python3
# An efficient Python 3 program to
# find 2's complement
# Function to find two's complement
def findTwoscomplement(str):
n = len(str)
# Traverse the string to get first
# '1' from the last of string
i = n - 1
while(i >= 0):
if (str[i] == '1'):
break
i -= 1
# If there exists no '1' concatenate 1
# at the starting of string
if (i == -1):
return '1'+str
# Continue traversal after the
# position of first '1'
k = i - 1
while(k >= 0):
# Just flip the values
if (str[k] == '1'):
str = list(str)
str[k] = '0'
str = ''.join(str)
else:
str = list(str)
str[k] = '1'
str = ''.join(str)
k -= 1
# return the modified string
return str
# Driver code
if __name__ == '__main__':
str = "00000101"
print(findTwoscomplement(str))
# This code is contributed by
# Sanjit_Prasad
C#
// An efficient c# program to find 2's complement
using System;
using System.Text;
class GFG
{
// Method to find two's complement
public static string findTwoscomplement(StringBuilder str)
{
int n = str.Length;
// Traverse the string to get
// first '1' from the last of string
int i;
for (i = n - 1 ; i >= 0 ; i--)
{
if (str[i] == '1')
{
break;
}
}
// If there exists no '1' concat 1
// at the starting of string
if (i == -1)
{
return "1" + str;
}
// Continue traversal after the
// position of first '1'
for (int k = i - 1 ; k >= 0; k--)
{
// Just flip the values
if (str[k] == '1')
{
str.Remove(k, k + 1 - k).Insert(k, "0");
}
else
{
str.Remove(k, k + 1 - k).Insert(k, "1");
}
}
// return the modified string
return str.ToString();
}
// Driver Code
public static void Main(string[] args)
{
StringBuilder str = new StringBuilder("00000101");
Console.WriteLine(findTwoscomplement(str));
}
}
// This code is contributed by Shrikant13
PHP
= 0 ; $i--)
if ($str[$i] == '1')
break;
// If there exists no '1' concatenate
// 1 at the starting of string
if ($i == -1)
return '1' + $str;
// Continue traversal after the
// position of first '1'
for ($k = $i-1 ; $k >= 0; $k--)
{
// Just flip the values
if ($str[$k] == '1')
$str[$k] = '0';
else
$str[$k] = '1';
}
// return the modified string
return $str;;
}
// Driver code
$str = "00000101";
echo findTwoscomplement($str);
// This code is contributed by jit.
?>
输出:
11111011