leetcode --83. 删除排序链表中的重复元素&&283. 移动零&&167. 两数之和 II - 输入有序数组&&344. 反转字符串

双指针

• [83. 删除排序链表中的重复元素](https://leetcode.cn/problems/remove-duplicates-from-sorted-list/)
• • 为什么最后要将left->next置为空
• [283. 移动零](https://leetcode.cn/problems/move-zeroes/)
• [167. 两数之和 II - 输入有序数组](https://leetcode.cn/problems/two-sum-ii-input-array-is-sorted/)
• [344. 反转字符串](https://leetcode.cn/problems/reverse-string/)

class Solution {
public:
    ListNode* deleteDuplicates(ListNode* head) {
       ListNode *left=head;
       if(head==nullptr){
           return head;
       }
       ListNode *right=head->next;
       while(right!=nullptr){
           if(right->val!=left->val){
               left->next=right ;
               left=right;
           }
           right=right->next;
       }
       left->next=nullptr;
        return head;
    }
};

class Solution {
public:
    void moveZeroes(vector& nums) {
        int t=remove(nums, 0);
        for(int i=t;i
            nums[i]=0;
        }
    }
    int remove(vector&nums,int val){
        int slow=0,fast=0;
        while(fast
            if(nums[fast]!=val){
                nums[slow]=nums[fast];
                slow++;
            }
            fast++;
        }
        return slow;
    }
};

class Solution {
public:
    vector twoSum(vector& numbers, int target) {
        vector a;
        // for(int i=0;i
        //     for(int j=i+1;j
        //         if(numbers[i]+numbers[j]==target){
        //             a.push_back(i+1);
        //             a.push_back(j+1);
        //             return a;
        //         }
        //     }
        // }
        int slow=0,fast=numbers.size()-1;
        while(slow
            if(numbers[slow]+numbers[fast]>target){
                fast--;
            }else if(numbers[slow]+numbers[fast]
                slow++;
            }else{
                a.push_back(slow+1);
                a.push_back(fast+1);
                return a;
            }
        }
        return a;
    }
};

class Solution {
public:
    void reverseString(vector& s) {
        int slow=0,fast=s.size()-1;
        while(slow<=fast){
            char temp=s[slow];
            s[slow]=s[fast];
            s[fast]=temp;
            slow++;
            fast--;
        }
    }
};