Second Largest

JavaView on GFG

Time: O(n)

Space: O(1)

Problem Overview

Find second largest element in array without sorting.

See our study guide for structured GFG and LeetCode practice.

Intuition

Find second largest element in array without sorting. Single pass tracking max and second max.

Algorithm

1max1 = max2 = INT_MIN. For each num: if num > max1: max2=max1, max1=num. Else if num > max2 and num != max1: max2=num.

Common Pitfalls

• Handle duplicates: second largest must be strictly less than largest. Return -1 if no second largest exists.

Second Largest.java

Java

// Approach: Single pass tracking the largest and second largest distinct values.
// Time: O(n) Space: O(1)
class Solution {
    public int getSecondLargest(int[] arr) {
        int l = arr[0];
        int sl = -1;
        for (int i = 1; i < arr.length; i++) {
            if (arr[i] > l) {
                sl = l;
                l = arr[i];
            } else if (arr[i] < l && arr[i] > sl) {
                sl = arr[i];
            }
        }
        return sl;
    }
}

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