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Find the element that appears once in an array where every oth… #3

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40 changes: 40 additions & 0 deletions Find the element that appears once in an array where every other element appears twice
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// C++ program to find
// element that appears once
#include <bits/stdc++.h>

using namespace std;

// function which find number
int singleNumber(int nums[],int n)
{
map<int,int> m;
long sum1 = 0,sum2 = 0;

for(int i = 0; i < n; i++)
{
if(m[nums[i]] == 0)
{
sum1 += nums[i];
m[nums[i]]++;
}
sum2 += nums[i];
}

// applying the formula.
return 2 * (sum1) - sum2;
}

// Driver code
int main()
{
int a[] = {2, 3, 5, 4, 5, 3, 4};
int n = 7;
cout << singleNumber(a,n) << "\n";

int b[] = {15, 18, 16, 18, 16, 15, 89};

cout << singleNumber(b,n);
return 0;
}

// This code is contributed by mohit kumar 29