Write a function that takes an array of numbers as input and returns the second largest number in the array. For example, if the input array is [5, 10, 7, 2, 1], the function should return 7.
Write a function called secondLargest that takes an array of numbers as its parameter and returns the second largest number in the array.
function secondLargest(arr) {
let largest = arr[0]; // initialize largest variable with first element of the array
let secondLargest = arr[0]; // initialize secondLargest variable with first element of the array
// iterate through the array starting from the second element
for (let i = 1; i < arr.length; i++) {
// if current element is greater than the largest, update both largest and secondLargest
if (arr[i] > largest) {
secondLargest = largest;
largest = arr[i];
}
// if current element is not greater than largest, but is greater than secondLargest, update secondLargest
else if (arr[i] > secondLargest && arr[i] < largest) {
secondLargest = arr[i];
}
}
return secondLargest; // return the second largest element in the array
}
The function first initializes two variables largest and secondLargest with the first element of the array. It then iterates through the rest of the array and updates these variables as necessary.
If the current element is greater than the largest variable, it updates both largest and secondLargest. If the current element is not greater than largest, but is greater than secondLargest, it updates only secondLargest.
Finally, the function returns the secondLargest variable, which should contain the second largest number in the array.
For example:
console.log(secondLargest([5, 10, 7, 2, 1])); // Output: 7
console.log(secondLargest([20, 10, 30, 40, 50])); // Output: 40
console.log(secondLargest([-10, -5, -20, -30, 0])); // Output: -5
In the first example, the input array is [5, 10, 7, 2, 1], and the function returns the second largest number, which is 7.
In the second example, the input array is [20, 10, 30, 40, 50], and the function returns the second largest number, which is 40.
In the third example, the input array is [-10, -5, -20, -30, 0], and the function returns the second largest number, which is -5.