数组链表

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode* deleteDuplicates(ListNode* head) {
        ListNode *dup = NULL;
        ListNode *cur = head;
        if(cur == NULL || cur->next == NULL) return head;
        ListNode *nxt = cur->next;
        while(nxt != NULL){
            if(cur->val == nxt->val){
                ListNode *dup = nxt;
                nxt = nxt->next;
                cur->next = nxt;
                delete dup;
            }else{
                cur = nxt;
                nxt = nxt->next;
            }
        }
        return head;
    }
};

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode* addTwoNumbers(ListNode* l1, ListNode* l2) {
        ListNode* ret, *tmp;
        int carry = 0, sum=0;
        ret = tmp = new ListNode(0);
        while(carry||l1||l2){
            sum = carry;
            if(l1)sum+=l1->val;
            if(l2)sum+=l2->val;
            carry = sum/10;
            tmp->val = sum%10;
            if(l1)l1 = l1->next?l1->next:NULL;
            if(l2)l2 = l2->next?l2->next:NULL;
            if(!l1 && !l2 && !carry)return ret;
            tmp->next = new ListNode(0);
            tmp=tmp->next;
        }
        return NULL;
    }
};

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode* mergeTwoLists(ListNode* l1, ListNode* l2) {
        if(!l1) return l2;
        if(!l2) return l1;
        ListNode *head, *retList;
        
        if(l1->val val){
            retList = head = l1;
            l1 = l1->next;
        }
        else{
            retList = head = l2;
            l2 = l2->next;
        }
        
        while(l1 && l2){
            if(l1->val val){
                head->next = l1;
                l1 = l1->next;
                head = head->next;
                head->next = NULL;
            }
            else{
                head->next = l2;
                l2 = l2->next;
                head = head->next;
                head->next = NULL;
            }
        }
        if(!l1) head->next = l2;
        if(!l2) head->next = l1;
        return retList;
   }
};

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode* reverseList(ListNode* head) {
        if(head == NULL || head->next == NULL) return head;
        ListNode* pre = NULL;
        ListNode* cur = head;
        ListNode* nx = cur->next;
        while(nx != NULL){
            cur->next = pre;
            pre = cur;
            cur = nx;
            nx = nx->next;
        }
        cur->next = pre;
        return cur;
    }
};

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode* sortList(ListNode* head) {
        ListNode*p = head;
        ListNode*q = NULL;
        int temp = 0;
        if(head == NULL) return head;
        for(; p!=NULL; p=p->next)
            for(q=p->next; q!=NULL; q=q->next){
                if(p->val > q->val){
                    temp = p->val;
                    p->val = q->val;
                    q->val = temp;
                }
            }
        return head;
    }
};

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode* removeNthFromEnd(ListNode* head, int n) {
        if(head == NULL || n == 0) return head;
        ListNode* slow = head;
        ListNode* fast = head;
        ListNode* pre = head;
        if(fast->next == NULL) return NULL; //[1] 1
        while(n>0){ //if n, slow will just point to the nth
            fast = fast->next;
            n--;
        }
        while(fast != NULL){
            fast = fast->next;
            pre = slow;
            slow = slow->next;
        }
        pre->next = slow->next;
        //if pre==slow==head [1,2] 2
        if(pre == slow) return head->next;
        
        return head;
    }
};

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    bool hasCycle(ListNode *head) {
        ListNode* slow = head;
        ListNode* fast = head;
        while(fast && fast->next){
            slow = slow->next;
            fast = fast->next->next; //2step
            if(slow == fast) return true;
        }
        return false;
    }
};

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode *getIntersectionNode(ListNode *headA, ListNode *headB) {
        ListNode* p1 = headA;
        ListNode* p2 = headB;
        while(p1 != p2){
            p1 = p1?p1->next:headB;
            p2 = p2?p2->next:headA;
        }
        return p1;
    }
};

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode* removeElements(ListNode* head, int val) {
        if(head == NULL) return head;
        ListNode* p = head;
        
        while (p->next != NULL){
            if(p->next->val == val){
                ListNode *tmp = p->next;
                p->next = p->next->next;
                delete tmp;
            }
            else{
                p = p->next;
            }
        }
        if(head->val == val)
            head = head->next;
        return head;
    }
};

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    void deleteNode(ListNode* node) {
        ListNode* p = node->next;
        node->val = p->val;
        node->next = p->next;
        delete p;
    }
};