2022-03-10 Daily-Challenge

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In: DailyChallenge

Today I have done leetcode's March LeetCoding Challenge with cpp.

March LeetCoding Challenge 10

Description

Add Two Numbers

You are given two non-empty linked lists representing two non-negative integers. The digits are stored in reverse order, and each of their nodes contains a single digit. Add the two numbers and return the sum as a linked list.

You may assume the two numbers do not contain any leading zero, except the number 0 itself.

Example 1:

img

Input: l1 = [2,4,3], l2 = [5,6,4]
Output: [7,0,8]
Explanation: 342 + 465 = 807.

Example 2:

Input: l1 = [0], l2 = [0]
Output: [0]

Example 3:

Input: l1 = [9,9,9,9,9,9,9], l2 = [9,9,9,9]
Output: [8,9,9,9,0,0,0,1]

Constraints:

  • The number of nodes in each linked list is in the range [1, 100].
  • 0 <= Node.val <= 9
  • It is guaranteed that the list represents a number that does not have leading zeros.

Solution

auto speedup = [](){
  cin.tie(nullptr);
  cout.tie(nullptr);
  ios::sync_with_stdio(false);
  return 0;
}();
class Solution {
public:
  ListNode* addTwoNumbers(ListNode* l1, ListNode* l2) {
    ListNode *newHead = new ListNode();
    ListNode *cur = newHead;
    int carry = 0;
    while(l1 && l2) {
      int val = l1->val + l2->val + carry;
      carry = val / 10;
      cur->next = new ListNode(val%10);
      cur = cur->next;
      l1 = l1->next;
      l2 = l2->next;
    }
    ListNode *rest = l1 ? l1 : l2;
    while(rest) {
      int val = rest->val + carry;
      carry = val / 10;
      cur->next = new ListNode(val%10);
      cur = cur->next;
      rest = rest->next;
    }
    if(carry) cur->next = new ListNode(carry);
    return newHead->next;
  }
};

// Accepted
// 1568/1568 cases passed (40 ms)
// Your runtime beats 71.08 % of cpp submissions
// Your memory usage beats 11.57 % of cpp submissions (71.6 MB)
Algorithm