程序员面试金典 2.4 链表分割

题目

我的题解

/*
struct ListNode {
int val;
struct ListNode *next;
ListNode(int x) : val(x), next(NULL) {}
};*/
class Partition {
public:
ListNode* partition(ListNode* pHead, int x) {
// write code here
ListNode* small     = NULL;
ListNode* big       = NULL;
ListNode* s_cur     = NULL;
ListNode* b_cur     = NULL;
ListNode* cur       = pHead;

while(cur != NULL) {
if((cur->val) < x) {
if(small == NULL) {
small = cur;
s_cur = small;
} else {
s_cur->next = cur;
s_cur = s_cur->next;
}
} else {
if(big == NULL) {
big = cur;
b_cur = big;
} else {
b_cur->next = cur;
b_cur = b_cur->next;
}
}
cur = cur->next;
}

if(s_cur == NULL)
return big;
s_cur->next = big;
if(b_cur != NULL)
b_cur->next = NULL;

return small;
}
};