leetcode-practice-pool's Introduction

Welcome to LeetCode-Practice-Pool 👋

Practice history for LeeCode

Author

👤 Yongchang He

Website: https://dev.to/yongchanghe
Twitter: @yongchanghe
Github: @hyc0812
LinkedIn: @yongchanghe

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Problem 2 Solution:

class Solution {
    public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
        ListNode dummyHead = new ListNode(0);
        ListNode curr = dummyHead;
        int carry = 0;

        while (l1 != null || l2 != null || carry != 0) {
            int x = (l1 != null) ? l1.val : 0;
            int y = (l2 != null) ? l2.val : 0;
            int sum = carry + x + y;
            carry = sum / 10;
            curr.next = new ListNode(sum % 10);
            curr = curr.next;
            if (l1 != null) {
                l1 = l1.next;
            }
            if (l2 != null) {
                l2 = l2.next;
            }
        }
        return dummyHead.next;
    }
}

Problem 3 Solution:

class Solution {
    public int lengthOfLongestSubstring(String s) {
        int a_pointer = 0;
        int b_pointer = 0;
        int max = 0;

        HashSet<Character> hash_set = new HashSet();

        while (b_pointer < s.length()) {
            if (!hash_set.contains(s.charAt(b_pointer))) {
                hash_set.add(s.charAt(b_pointer));
                b_pointer++;
                max = Math.max(hash_set.size(), max);
            } else {
                hash_set.remove(s.charAt(a_pointer));
                a_pointer++;
            }
        }
        return max;
    }
}

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