Find the Second Largest Element in an Array

📌 Definition:

📖 Detailed Explanation:

Track largest and secondLargest together. For each element: if it beats largest, secondLargest becomes the old largest and largest updates; else if it is between secondLargest and largest (and, for the distinct variant, not equal to largest), update secondLargest. O(n). Sorting works but is slower.

💻 Solutions:

• Java
• JavaScript
• Python

public static int secondLargest(int[] a) {
    int first = Integer.MIN_VALUE, second = Integer.MIN_VALUE;
    for (int x : a) {
        if (x > first) { second = first; first = x; }
        else if (x > second && x != first) { second = x; }
    }
    return second;
}

function secondLargest(a) {
  let first = -Infinity, second = -Infinity;
  for (const x of a) {
    if (x > first) { second = first; first = x; }
    else if (x > second && x !== first) { second = x; }
  }
  return second;
}

def second_largest(a):
    first = second = float('-inf')
    for x in a:
        if x > first:
            second, first = first, x
        elif x > second and x != first:
            second = x
    return second

🔑 Key Points:

• Single O(n) pass with two trackers
• Decide distinct vs allow duplicates
• Handle length < 2 and all-equal arrays
• Initialize to negative infinity

🌍 Real-World Example: