Add Finding the Second Largest Element (TheAlgorithms#198)

siva-balan · Panquesito7 · web-flow · commit 0721d6063247 · 2022-10-28T18:37:41.000-05:00
* Create Find Second Largest Element.md

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* Update en/Selection Algorithms/Find Second Largest Element.md

Co-authored-by: David Leal &lt;halfpacho@gmail.com&gt;

* Create Find Second Largest Element.md

* Update Find Second Largest Element.md

Co-authored-by: David Leal &lt;halfpacho@gmail.com&gt;
diff --git a/en/Selection Algorithms/Find Second Largest Element.md b/en/Selection Algorithms/Find Second Largest Element.md
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+# Find Second Largest Element
+
+#### Problem statement
+
+Given an unsorted array, write a function to find the second largest element in the array.
+
+#### Approach
+
+- Find the largest element in the array by traversing through the array using a loop and store the value in a variable (for ex: a )
+- Assign a variable to store the negative infinite value, which stores the least value (for ex: b )
+- Run a loop from zero to the size of the array.
+- Now check whether the current element is greater than variable "b" and also not equal to variable "a", which is the largest number in the array.
+- if the above condition is true, then the variable b stores the current element.
+
+#### Time Complexity
+
+- Best case: `O(n)`
+- Average case: `O(n)`
+- Worst case: `O(n)`
+
+#### Space Complexity
+
+Worst case: `O(1)`
+
+#### Example
+
+```txt
+arr =    [2, 5,  3,  9,  12, 34, 25]
+Indexes:  0   1   2   3   4   5   6
+a = max(arr) 
+(a = 34)
+b = float("-inf")
+
+Traverse elements from i = 0 to i = 6
+i = 0
+Check if b < arr[i] (arr[0]) and arr[0] != a
+True : b = arr[0] (b = 2)
+
+i = 1
+Check if b < arr[i] (arr[1]) and arr[1] != a
+True : b = arr[0] (b = 5)
+
+i = 2
+Check if b < arr[i] (arr[2]) and arr[2] != a
+False : As b = 5 is greater than the current element arr[2] = 3
+continues with the loop
+
+i = 3
+Check if b < arr[i] (arr[3]) and arr[3] != a
+True : b = arr[3] (b = 9)
+
+i = 4
+Check if b < arr[i] (arr[4]) and arr[4] != a
+True : b = arr[4] (b = 12)
+
+i = 5
+Check if b < arr[i] (arr[5]) and arr[5] != a
+False:  As current element is equal to the variable "a" which stores the highest value in the array
+continues with the loop
+
+i = 6
+Check if b < arr[i] (arr[6]) and arr[6] != a
+True : b = arr[6] (b = 25)
+
+Now we get the value 25 in the variable "b", which is the second highest value in the array.
+```
+
+#### Code Implementation Links
+
+[JavaScript](https://github.com/TheAlgorithms/JavaScript/blob/master/Sorts/FindSecondLargestElement.js)
+
+#### Video Explanation
+
+[Video explaining 2 approaches](https://www.youtube.com/watch?v=Mv8jhYQEbkA)
