# Second largest element

### Problem Statement:

Given an array of integers, find the second largest element in the array.

### Steps to Solve the Problem:

1. **Initialization:**
    
    * Initialize two variables: `firstLargest` and `secondLargest` to the smallest possible integer value (`Integer.MIN_VALUE`).
        
2. **Iterate Through the Array:**
    
    * For each element in the array, compare it with `firstLargest` and `secondLargest` and update these variables accordingly:
        
        * If the current element is greater than `firstLargest`, update `secondLargest` to `firstLargest` and then update `firstLargest` to the current element.
            
        * If the current element is greater than `secondLargest` but not equal to `firstLargest`, update `secondLargest` to the current element.
            
3. **Return the Result:**
    
    * After the loop, check if `secondLargest` is still `Integer.MIN_VALUE`. If so, return `null`, meaning there is no second largest element. Otherwise, return `secondLargest`.
        

### Dry Run:

Let's perform a dry run with the array `[12, 35, 1, 10, 34, 1]`.

**Initial State:**

* `firstLargest = Integer.MIN_VALUE` (`-2147483648`)
    
* `secondLargest = Integer.MIN_VALUE` (`-2147483648`)
    

**Array Iteration:**

1. **First Element: 12**
    
    * Compare 12 with `firstLargest` (`-2147483648`):
        
        * 12 > `firstLargest`, so update `secondLargest` to `firstLargest` (`-2147483648`) and `firstLargest` to 12.
            
    * **State:**
        
        * `firstLargest = 12`
            
        * `secondLargest = -2147483648`
            
2. **Second Element: 35**
    
    * Compare 35 with `firstLargest` (12):
        
        * 35 > `firstLargest`, so update `secondLargest` to `firstLargest` (12) and `firstLargest` to 35.
            
    * **State:**
        
        * `firstLargest = 35`
            
        * `secondLargest = 12`
            
3. **Third Element: 1**
    
    * Compare 1 with `firstLargest` (35):
        
        * 1 is not greater than `firstLargest`, so check if it's greater than `secondLargest` (12):
            
        * 1 is not greater than `secondLargest`, so no changes.
            
    * **State:**
        
        * `firstLargest = 35`
            
        * `secondLargest = 12`
            
4. **Fourth Element: 10**
    
    * Compare 10 with `firstLargest` (35):
        
        * 10 is not greater than `firstLargest`, so check if it's greater than `secondLargest` (12):
            
        * 10 is not greater than `secondLargest`, so no changes.
            
    * **State:**
        
        * `firstLargest = 35`
            
        * `secondLargest = 12`
            
5. **Fifth Element: 34**
    
    * Compare 34 with `firstLargest` (35):
        
        * 34 is not greater than `firstLargest`, so check if it's greater than `secondLargest` (12):
            
        * 34 > `secondLargest`, so update `secondLargest` to 34.
            
    * **State:**
        
        * `firstLargest = 35`
            
        * `secondLargest = 34`
            
6. **Sixth Element: 1**
    
    * Compare 1 with `firstLargest` (35):
        
        * 1 is not greater than `firstLargest`, so check if it's greater than `secondLargest` (34):
            
        * 1 is not greater than `secondLargest`, so no changes.
            
    * **Final State:**
        
        * `firstLargest = 35`
            
        * `secondLargest = 34`
            

### Final Result:

* The second largest element in the array is **34**.
    

### Java Code Recap:

```java
javaCopy codepublic class SecondLargestElement {
    public static Integer findSecondLargest(int[] arr) {
        if (arr.length < 2) {
            return null; // Not enough elements
        }

        int firstLargest = Integer.MIN_VALUE;
        int secondLargest = Integer.MIN_VALUE;

        for (int i = 0; i < arr.length; i++) {
            if (arr[i] > firstLargest) {
                secondLargest = firstLargest;
                firstLargest = arr[i];
            } else if (arr[i] > secondLargest && arr[i] != firstLargest) {
                secondLargest = arr[i];
            }
        }

        return secondLargest == Integer.MIN_VALUE ? null : secondLargest;
    }

    public static void main(String[] args) {
        int[] arr = {12, 35, 1, 10, 34, 1};
        Integer result = findSecondLargest(arr);

        if (result != null) {
            System.out.println("The second largest element is: " + result);
        } else {
            System.out.println("There is no second largest element.");
        }
    }
}
```

This dry run shows how the algorithm processes each element in the array and correctly identifies the second largest element.