Occurence of an integer in a Linked List

JavaView on GFG

Time: O(n)

Space: O(1)

Intuition

Count occurrences of a target value in linked list. Linear scan.

Algorithm

1Traverse list, increment counter each time node.val == target.

Common Pitfalls

•Simple O(n) traversal. Handle empty list (return 0).

Occurence of an integer in a Linked List.java

Java

// Approach: Traverse list and count nodes with matching value.
// Time: O(n) Space: O(1)
class Node {
    int data;
    Node next;

    Node(int key) {
        data = key;
        next = null;
    }
}

class Solution {
    public static int count(Node head, int key) {
        int count = 0;
        Node temp = head;
        while (temp != null) {
            if (temp.data == key) {
                count++;
            }
            temp = temp.next;
        }
        return count;
    }
}

Was this solution helpful?