PROBLEM

Given an array of numbers, write a function to determine whether

it contains duplicates. (Use a double for loop.)

*/

​

function hasDuplicates(numbers) {

  for (let i = 0; i < numbers.length; i++) {

    for (let j = i + 1; j < numbers.length; j++) {

      if (numbers[i] === numbers[j]) {

        return true;

      }

    }

  }

  return false;

}

​

// tests

​

// expect true

console.log(hasDuplicates([2, 2, 3, 5, 7]));

console.log(hasDuplicates([2, 3, 5, 7, 2]));

console.log(hasDuplicates([2, 3, 5, 5, 7]));

console.log(hasDuplicates([2, 5, 3, 5, 7]));

console.log(hasDuplicates([2, 5, 5, 5, 7]));

​

// expect false

console.log(hasDuplicates([2, 3, 5, 7, 9]));

console.log(hasDuplicates([2]));

console.log(hasDuplicates([]));