Day 8

Mothers and Father's day Challenges day 
Day 8 :
Topic: Linked List - Odd Even Linked List - https://lnkd.in/gpMgj7eU
Code - 
/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode() {}
 *     ListNode(int val) { this.val = val; }
 *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
 * }
 */
class Solution {
    public ListNode oddEvenList(ListNode head) {
        if (head == null) {
            return null;
        }
        ListNode a = head;
        ListNode b = head.next, c = b;
        while (b != null && b.next != null) {
            a.next = b.next;
            a = a.next;
            b.next = a.next;
            b = b.next;
        }
        a.next = c;
        return head;
    }
}
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Topic: Math based - Excel Sheet Column Number - https://lnkd.in/g2JKSqZK
Code-
class Solution {
    public int titleToNumber(String columnTitle) {
        int ans = 0;
        for (int i = 0; i < columnTitle.length(); ++i) {
            ans = ans * 26 + (columnTitle.charAt(i) - 'A' + 1);
        }
        return ans;
    }
}