Leetcode 2 Add Numbers

/**
* Id:2
* Name:add-Numbers
* Data structure:linked List
* Time Complexity:
* Space Complexity:
* Tag:linklist
* Difficult:medium

* Problem:
* You are given, linked lists representing, and non-negative numbers.
* The digits is stored in reverse order and all of their nodes contain a single digit.
* Add the numbers and return it as a linked list.
* Input: (2, 4, 3) + (5, 6, 4)
* 8 Output:7, 0

Idea one: main note who first traverse the end, and pay attention to the problem of rounding, carry, is when there is no new node, but there are carry, it is necessary to add a new node in.

In the two lists are not all finished, add, carry, and then merge the L2 into the L1 inside, and then let the L1 go through, complete all the carry operations.

Idea two: Create a brand new list, then add each value to the L1,l2,carry each time, and finally return a new list.

1 classSolution {2  Public:3ListNode *addtwonumbers (ListNode *l1, ListNode *L2) {4         if(L1 = =NULL)5             returnL2;6         if(L2 = =NULL)7             returnL1;8 9ListNode *fakenode1 =NewListNode (0);TenListNode *fakenode2 =NewListNode (0); OneFakeNode1-Next =L1; AFakeNode2-Next =L2; -ListNode *P1 =FakeNode1; -ListNode *P2 =FakeNode2; the         intcarry =0; -         intsum =0; -  -          while(P1->next && p2->next) +         { -P1 = p1->Next; +P2 = p2->Next; Asum = carry + P1->val + p2->Val; atcarry = sum/Ten; -P1->val = sum%Ten;  -               -         } -          -         if(P1->next==null && p2->next!=NULL) in         { -P1->next = p2->Next; to         } +         DeleteP2; -         DeleteFakeNode2; the          while(p1->next) *         { $P1 = p1->Next;Panax Notoginsengsum = carry + p1->Val; -carry = sum/Ten; theP1->val = sum%Ten; +         } A        if(carry!=0) the         { +ListNode *last =NewListNode (carry); -P1->next =Last ;  $         }   $         returnFakenode1->Next; -     } -};

Idea two:

1 classSolution {2  Public:3ListNode *addtwonumbers (ListNode *l1, ListNode *L2) {4ListNode *dummy =NewListNode (0), *p =dummy;5         intcarry =0;6          while(L1 | | l2 | |carry) {7             if(L1) {8Carry+=l1->Val;9L1 = l1->Next;Ten             } One             if(L2) { ACarry+=l2->Val; -L2 = l2->Next; -             } theP->next =NewListNode (carry%Ten);//every time create a new node. -Carry/=Ten; -p = p->Next; -         } +         returnDummy->Next; -     } +};

Leetcode 2 Add Numbers