在二进制数组中检查子数组表示的数字是奇数还是偶数

原文： https://www.geeksforgeeks.org/check-binary-array-number-represented-subarray-odd-even/

给定一个数组，使其所有项均为 0 或 1。您需要告诉子数组a[l..r]表示的数字为奇数或偶数。

示例：

Input : arr = {1, 1, 0, 1}
        l = 1, r = 3
Output : odd
        number represented by arr[l...r] is 
        101 which 5 in decimal form which is 
        odd

Input :  arr = {1, 1, 1, 1}
         l = 0, r = 3
Output : odd

这里要注意的重要一点是，二进制形式的所有奇数均以 1 作为其最右边的位，所有偶数均以 0 作为其最右边的位。

原因很简单，除了最右边的位以外，所有其他位都具有偶数，偶数之和始终为偶数。现在，最右边的位可以具有 1 或 0 的值，因为我们知道偶数+奇数=奇数，因此当最右边的位为 1 时，数字为奇数；为 0 时，数字为偶数。

因此，要解决此问题，我们只需要检查a[r]是 0 还是 1，并因此打印奇数或偶数。

C++

// C++ program to find if a subarray 
// is even or odd. 
#include<bits/stdc++.h> 
using namespace std; 

// prints if subarray is even or odd 
void checkEVENodd (int arr[], int n, int l, int r) 
{ 
    // if arr[r] = 1 print odd 
    if (arr[r] == 1) 
        cout << "odd" << endl; 

    // if arr[r] = 0 print even 
    else
        cout << "even" << endl; 
} 

// driver code 
int main() 
{ 
    int arr[] = {1, 1, 0, 1}; 
    int n = sizeof(arr)/sizeof(arr[0]); 
    checkEVENodd (arr, n, 1, 3); 
    return 0; 
}

Java

// java program to find if a subarray 
// is even or odd. 
import java.io.*; 

class GFG  
{ 
    // prints if subarray is even or odd 
    static void checkEVENodd (int arr[], int n, int l, int r) 
    { 
        // if arr[r] = 1 print odd 
        if (arr[r] == 1) 
            System.out.println( "odd") ; 

        // if arr[r] = 0 print even 
        else
            System.out.println ( "even") ; 
    } 

    // driver code 
    public static void main (String[] args)  
    { 
        int arr[] = {1, 1, 0, 1}; 
        int n = arr.length; 
        checkEVENodd (arr, n, 1, 3); 


    } 
} 

// This article is contributed by vt_m.

Python3

# Python3 program to find if a  
# subarray is even or odd. 

# Prints if subarray is even or odd 
def checkEVENodd (arr, n, l, r): 

    # if arr[r] = 1 print odd 
    if (arr[r] == 1): 
        print("odd") 

    # if arr[r] = 0 print even 
    else: 
        print("even") 

# Driver code 
arr = [1, 1, 0, 1] 
n = len(arr) 
checkEVENodd (arr, n, 1, 3) 

# This code is contributed by Anant Agarwal.

C

// C# program to find if a subarray 
// is even or odd. 
using System; 

class GFG { 

    // prints if subarray is even or odd 
    static void checkEVENodd (int []arr,  
                     int n, int l, int r) 
    { 

        // if arr[r] = 1 print odd 
        if (arr[r] == 1) 
            Console.WriteLine( "odd") ; 

        // if arr[r] = 0 print even 
        else
            Console.WriteLine( "even") ; 
    } 

    // driver code 
    public static void Main()  
    { 

        int []arr = {1, 1, 0, 1}; 
        int n = arr.Length; 

        checkEVENodd (arr, n, 1, 3); 
    } 
} 

// This article is contributed by Anant Agarwal.

PHP

<?php 
// PHP program to find if a subarray 
// is even or odd. 

// prints if subarray is even or odd 
function checkEVENodd ($arr, $n, $l, $r) 
{ 
    // if arr[r] = 1 print odd 
    if ($arr[$r] == 1) 
        echo "odd", "\n"; 

    // if arr[r] = 0 print even 
    else
        echo "even", "\n"; 
} 

// Driver code 
$arr = array(1, 1, 0, 1); 
$n = sizeof($arr); 
checkEVENodd ($arr, $n, 1, 3); 

// This code is Contributed by Ajit 
?>

输出：

odd

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