今天刷的小题一道，微软14年校园招聘笔试唯一一道编程题。
Given a singly linked list L: (L0 , L1 , L2...Ln-1 , Ln). Write a program to reorder it so that it becomes(L0 , Ln , L1 , Ln-1 , L2 , Ln-2...).
1 struct Node 2 { 3 int val_; 4 Node* next; 5 };
Notes:
1、Space Complexity should be O(1)
2、Only the ".next" field of a node is modifiable.
代码：
1 Node* ReorderList(Node* sll) 2 { 3 if(sll == NULL || sll->next == NULL || sll->next->next == NULL) 4 return sll; 5 Node* p1 = sll; 6 Node* p2 = sll->next; 7 Node* p3 = sll; 8 Node* p4 = sll->next; 9 while(p4->next != NULL) 10 { 11 p3 = p3->next; 12 p4 = p4->next; 13 } 14 while(p2->next != NULL) 15 { 16 p1->next = p4; 17 p4->next = p2; 18 p3->next = NULL; 19 p1 = p2; 20 p2 = p2->next; 21 p4 = sll; 22 while(p4->next != p3) 23 p4 = p4->next; 24 p3 = p4; 25 p4 = p4->next; 26 if(p2 == NULL) 27 break; 28 } 29 return sll; 30 }
自己多动手没坏处~