Java program to find second largest number in an array

If you want to practice data structure and algorithm programs, you can go through data structure and algorithm interview questions.

In this post, we will see how to find the second largest number in an array.

Problem :

Given an unsorted array, you need to find the second largest element in the array in o(n) time complexity.
For example:

int[] arr1={7,5,6,1,4,2};
Second largest element in the array : 6

Solution:

You can sort the array and then return second last element in the array but it will be done in o(nlogn)  time,

Algorithm:

  • Initialize highest and secondHighest with minimum possible value.
  • Iterate over array.
  • If current element is greater than highest
    • Assign secondHighest = highest
    • Assign highest = currentElement
  • Else if current element is greater than secondHighest
    • Assign secondHighest =current element.

Java Program to find second largest number in array:

Create the main java class named FindSecondLargestMain.java
When you run above program, you will get below output:

Second largest element in the array : 6

That’s all about how to find second largest number in an array.


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Comments

  1. Hi, this code will fail if an array contains duplicate which is also happened to be largest element.
    Example: arr[] = {7, 8, 8, 1, 4, 2}

  2. If we change else id condition code works fine all cases,
    else if (array[i] > secondHighest && array[i] != highest){
    secondHighest = array[i];
    }

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