Binary search in a list of integers

Problem

Given a list of integers and a target value, write a function that returns the index of the target value if it is present in the list, or -1 if it is not present.
Example input: [1, 2, 3, 4, 5], 3
Example output: 2

Solution

This solution is in JavaScript. Our A.I. can create solutions in multiple languages.

kayakane

// Solution:
// The optimal solution is to use a for loop to iterate through the array and check if the current element is equal to the target value.
// If it is, return the index of the current element.
// If the loop finishes without returning, return -1.
// This solution is optimal because it only iterates through the array once, and therefore has a time complexity of O(n).

function findIndex(arr, target) {
  for (let i = 0; i < arr.length; i++) {
    if (arr[i] === target) {
      return i;
    }
  }
  return -1;
}

console.log(findIndex([1, 2, 3, 4, 5], 3)); // 2
console.log(findIndex([1, 2, 3, 4, 5], 6)); // -1