元素等于所有剩余元素的总和

给定一个由N个正元素组成的数组。任务是找到一个元素，该元素等于数组除自身之外的所有元素的总和。

例子：

Input: arr[] = {1, 2, 3, 6}
Output: 6
6 is the element which is equal to the sum of all 
remaining elements i.e. 1 + 2+ 3 = 6

Input: arr[] = {2, 2, 2, 2}
Output: -1

方法：首先，找到数组所有元素的总和。然后遍历每个元素并检查条件是否为(a [i] == sum-a [i]) 。如果为true，则打印该a [i] ，否则，如果未找到此元素，则打印“ -1”。

下面是上述方法的实现：

C++

// C++ implementation of the above approach
#include 
#define ll long long int
using namespace std;
  
// Function to find the element
int findEle(int arr[], int n)
{
    // sum is use to store
    // sum of all elements
    // of array
    ll sum = 0;
  
    for (int i = 0; i < n; i++)
        sum += arr[i];
  
    // iterate over all elements
    for (int i = 0; i < n; i++)
        if (arr[i] == sum - arr[i])
            return arr[i];
  
    return -1;
}
  
// Driver code
int main()
{
    int arr[] = { 1, 2, 3, 6 };
    int n = sizeof(arr) / sizeof(arr[0]);
    cout << findEle(arr, n);
    return 0;
}

Java

// Java implementation of the above approach
  
import java.io.*;
  
class GFG {
  
  
// Function to find the element
static int findEle(int arr[], int n)
{
    // sum is use to store
    // sum of all elements
    // of array
    int sum = 0;
  
    for (int i = 0; i < n; i++)
        sum += arr[i];
  
    // iterate over all elements
    for (int i = 0; i < n; i++)
        if (arr[i] == sum - arr[i])
            return arr[i];
  
    return -1;
}
  
// Driver code
  
    public static void main (String[] args) {
        int arr[] = { 1, 2, 3, 6 };
    int n = arr.length;
    System.out.print(findEle(arr, n));
    }
}
// This code is contributed by shs..

Python3

# Python 3 implementation of 
# the above approach
  
# Function to find the element
def findEle(arr, n) :
      
    # sum is use to store 
    # sum of all elements 
    # of array 
    sum = 0
      
    for i in range(n) :
        sum += arr[i]
      
    # iterate over all elements
    for i in range(n) :
        if arr[i] == sum - arr[i] :
            return arr[i]
      
    return -1
  
# Driver Code
if __name__ == "__main__" :
      
    arr = [1, 2, 3, 6 ]
    n = len(arr)
    print(findEle(arr, n))
  
# This code is contributed by Ryuga

C#

// C# implementation of the 
// above approach 
using System; 
  
class GFG 
{ 
  
// Function to find the element 
static int findEle(int []arr, int n) 
{ 
    // sum is use to store 
    // sum of all elements 
    // of array 
    int sum = 0; 
  
    for (int i = 0; i < n; i++) 
        sum += arr[i]; 
  
    // iterate over all elements 
    for (int i = 0; i < n; i++) 
        if (arr[i] == sum - arr[i]) 
            return arr[i]; 
  
    return -1; 
} 
  
// Driver code 
static public void Main (String []args)
{ 
    int []arr = { 1, 2, 3, 6 }; 
    int n = arr.Length; 
    Console.WriteLine(findEle(arr, n)); 
} 
} 
  
// This code is contributed 
// by Arnab Kundu

输出：

6

注意：以上问题可以使用“检查数组是否具有等于所有其余元素之和的元素”中的概念来解决。