Coding Challenge Practice – Question 77

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The task is to implement a function that quickly targets an integer that appears once, given an array of integers that appear twice.

The boilerplate code 

function findSingle(arr) {
  // your code here
}

The single integer can be quickly targeted using the XOR trick (^). Using the example 

a ^ a = 0

Two numbers that are the same cancel out. So, using the XOR method, all numbers in pairs will cancel out. 

for(let num of arr) {
 result ^= num
}

Then the remaining integer is returned. The final code: 

function findSingle(arr) {
  // your code here
  let result = 0;

  for(let num of arr) {
    result ^= num;
  }

  return result;
}

That’s all folks!

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