给定一个数组整数。任务是找到对(i,j)的对数,以使A [i]和A [j]为偶数。
例子:
Input: N = 4, A[] = { 5, 1, 3, 2 }
Output: 3
Since pair of A[] are:
( 5, 1 ), ( 5, 3 ), ( 5, 2 ), ( 1, 3 ), ( 1, 2 ), ( 3, 2 )
5 AND 1 = 1, 5 AND 3 = 1, 5 AND 2 = 0,
1 AND 3 = 1, 1 AND 2 = 0,
3 AND 2 = 2
Total even pair A( i, j ) = 3
Input : N = 6, A[] = { 5, 9, 0, 6, 7, 3 }
Output : 9
Since pair of A[] =
( 5, 9 ) = 1, ( 5, 0 ) = 0, ( 5, 6 ) = 4, ( 5, 7 ) = 5, ( 5, 3 ) = 1,
( 9, 0 ) = 0, ( 9, 6 ) = 0, ( 9, 7 ) = 1, ( 9, 3 ) = 1,
( 0, 6 ) = 0, ( 0, 7 ) = 0, ( 0, 3 ) = 0,
( 6, 7 ) = 6, ( 6, 3 ) = 2,
( 7, 3 ) = 3
幼稚的方法是检查每一对,并打印偶数对。
下面是上述方法的实现:
C++
// C++ program to count pair with
// bitwise-AND as even number
#include
using namespace std;
// Function to count number of pairs EVEN bitwise AND
int findevenPair(int A[], int N)
{
int i, j;
// variable for counting even pairs
int evenPair = 0;
// find all pairs
for (i = 0; i < N; i++) {
for (j = i + 1; j < N; j++) {
// find AND operation
// to check evenpair
if ((A[i] & A[j]) % 2 == 0)
evenPair++;
}
}
// return number of even pair
return evenPair;
}
// Driver Code
int main()
{
int a[] = { 5, 1, 3, 2 };
int n = sizeof(a) / sizeof(a[0]);
cout << findevenPair(a, n) << endl;
return 0;
}
Java
// Java program to count pair with
// bitwise-AND as even number
import java.io.*;
class GFG
{
// Function to count number of
// pairs EVEN bitwise AND
static int findevenPair(int []A,
int N)
{
int i, j;
// variable for counting even pairs
int evenPair = 0;
// find all pairs
for (i = 0; i < N; i++)
{
for (j = i + 1; j < N; j++)
{
// find AND operation
// to check evenpair
if ((A[i] & A[j]) % 2 == 0)
evenPair++;
}
}
// return number of even pair
return evenPair;
}
// Driver Code
public static void main (String[] args)
{
int []a = { 5, 1, 3, 2 };
int n = a.length;
System.out.println(findevenPair(a, n));
}
}
// This code is contributed by anuj_67..
Python3
# Python 3 program to count pair with
# bitwise-AND as even number
# Function to count number of
# pairs EVEN bitwise AND
def findevenPair(A, N):
# variable for counting even pairs
evenPair = 0
# find all pairs
for i in range(0, N):
for j in range(i + 1, N):
# find AND operation to
# check evenpair
if ((A[i] & A[j]) % 2 == 0):
evenPair += 1
# return number of even pair
return evenPair
# Driver Code
a = [ 5, 1, 3, 2 ]
n = len(a)
print(findevenPair(a, n))
# This code is contributed
# by PrinciRaj1992
C#
// C# program to count pair with
// bitwise-AND as even number
using System;
class GFG
{
// Function to count number of
// pairs EVEN bitwise AND
static int findevenPair(int []A,
int N)
{
int i, j;
// variable for counting even pairs
int evenPair = 0;
// find all pairs
for (i = 0; i < N; i++)
{
for (j = i + 1; j < N; j++)
{
// find AND operation
// to check evenpair
if ((A[i] & A[j]) % 2 == 0)
evenPair++;
}
}
// return number of even pair
return evenPair;
}
// Driver Code
public static void Main ()
{
int []a = { 5, 1, 3, 2 };
int n = a.Length;
Console.WriteLine(findevenPair(a, n));
}
}
// This code is contributed by anuj_67..
PHP
Javascript
C++
// C++ program to count pair with
// bitwise-AND as even number
#include
using namespace std;
// Function to count number of pairs
// with EVEN bitwise AND
int findevenPair(int A[], int N)
{
int count = 0;
// count odd numbers
for (int i = 0; i < N; i++)
if (A[i] % 2 != 0)
count++;
// count odd pairs
int oddCount = count * (count - 1) / 2;
// return number of even pair
return (N * (N - 1) / 2) - oddCount;
}
// Driver Code
int main()
{
int a[] = { 5, 1, 3, 2 };
int n = sizeof(a) / sizeof(a[0]);
cout << findevenPair(a, n) << endl;
return 0;
}
Java
// Java program to count pair with
// bitwise-AND as even number
import java.io.*;
class GFG {
// Function to count number of pairs
// with EVEN bitwise AND
static int findevenPair(int A[], int N)
{
int count = 0;
// count odd numbers
for (int i = 0; i < N; i++)
if (A[i] % 2 != 0)
count++;
// count odd pairs
int oddCount = count * (count - 1) / 2;
// return number of even pair
return (N * (N - 1) / 2) - oddCount;
}
// Driver Code
public static void main (String[] args) {
int a[] = { 5, 1, 3, 2 };
int n =a.length;
System.out.print( findevenPair(a, n));
}
}
// This code is contributed by anuj_67..
Python3
# Python 3 program to count pair with
# bitwise-AND as even number
# Function to count number of pairs
# with EVEN bitwise AND
def findevenPair(A, N):
count = 0
# count odd numbers
for i in range(0, N):
if (A[i] % 2 != 0):
count += 1
# count odd pairs
oddCount = count * (count - 1) / 2
# return number of even pair
return (int)((N * (N - 1) / 2) - oddCount)
# Driver Code
a = [5, 1, 3, 2 ]
n = len(a)
print(findevenPair(a, n))
# This code is contributed
# by PrinciRaj1992
C#
// C# program to count pair with
// bitwise-AND as even number
using System;
public class GFG{
// Function to count number of pairs
// with EVEN bitwise AND
static int findevenPair(int []A, int N)
{
int count = 0;
// count odd numbers
for (int i = 0; i < N; i++)
if (A[i] % 2 != 0)
count++;
// count odd pairs
int oddCount = count * (count - 1) / 2;
// return number of even pair
return (N * (N - 1) / 2) - oddCount;
}
// Driver Code
static public void Main (){
int []a = { 5, 1, 3, 2 };
int n =a.Length;
Console.WriteLine( findevenPair(a, n));
}
}
// This code is contributed by ajit
PHP
Javascript
输出:
3
一种有效的方法是观察两个数字的按位与,即使两个数字中的至少一个是偶数也将是偶数。因此,计算数组中所有的奇数,例如count 。现在,具有两个奇数元素的对的数量将为count *(count-1)/ 2 。
因此,具有至少一个偶数元素的元素数将是:
Total Pairs - Count of pair with both odd elements
下面是上述方法的实现:
C++
// C++ program to count pair with
// bitwise-AND as even number
#include
using namespace std;
// Function to count number of pairs
// with EVEN bitwise AND
int findevenPair(int A[], int N)
{
int count = 0;
// count odd numbers
for (int i = 0; i < N; i++)
if (A[i] % 2 != 0)
count++;
// count odd pairs
int oddCount = count * (count - 1) / 2;
// return number of even pair
return (N * (N - 1) / 2) - oddCount;
}
// Driver Code
int main()
{
int a[] = { 5, 1, 3, 2 };
int n = sizeof(a) / sizeof(a[0]);
cout << findevenPair(a, n) << endl;
return 0;
}
Java
// Java program to count pair with
// bitwise-AND as even number
import java.io.*;
class GFG {
// Function to count number of pairs
// with EVEN bitwise AND
static int findevenPair(int A[], int N)
{
int count = 0;
// count odd numbers
for (int i = 0; i < N; i++)
if (A[i] % 2 != 0)
count++;
// count odd pairs
int oddCount = count * (count - 1) / 2;
// return number of even pair
return (N * (N - 1) / 2) - oddCount;
}
// Driver Code
public static void main (String[] args) {
int a[] = { 5, 1, 3, 2 };
int n =a.length;
System.out.print( findevenPair(a, n));
}
}
// This code is contributed by anuj_67..
Python3
# Python 3 program to count pair with
# bitwise-AND as even number
# Function to count number of pairs
# with EVEN bitwise AND
def findevenPair(A, N):
count = 0
# count odd numbers
for i in range(0, N):
if (A[i] % 2 != 0):
count += 1
# count odd pairs
oddCount = count * (count - 1) / 2
# return number of even pair
return (int)((N * (N - 1) / 2) - oddCount)
# Driver Code
a = [5, 1, 3, 2 ]
n = len(a)
print(findevenPair(a, n))
# This code is contributed
# by PrinciRaj1992
C#
// C# program to count pair with
// bitwise-AND as even number
using System;
public class GFG{
// Function to count number of pairs
// with EVEN bitwise AND
static int findevenPair(int []A, int N)
{
int count = 0;
// count odd numbers
for (int i = 0; i < N; i++)
if (A[i] % 2 != 0)
count++;
// count odd pairs
int oddCount = count * (count - 1) / 2;
// return number of even pair
return (N * (N - 1) / 2) - oddCount;
}
// Driver Code
static public void Main (){
int []a = { 5, 1, 3, 2 };
int n =a.Length;
Console.WriteLine( findevenPair(a, n));
}
}
// This code is contributed by ajit
的PHP
Java脚本
输出:
3
时间复杂度:O(N)
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