LeetCode -3 - (字符串相加、最大连续1的个数＜ⅠⅢ＞、考试的最大困扰度、删除链表的倒数第N个结点)

S atur

已于 2022-04-03 19:34:48 修改

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分类专栏：模拟· 文章标签： leetcode

于 2022-03-29 15:17:29 首次发布

本文链接：https://blog.youkuaiyun.com/Satur9/article/details/123815447

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本文介绍了几种实用的字符串和链表操作方法，包括两数相加、查找连续字符最大长度、翻转链表等常见算法题目的解决方案，并提供详细的C++实现代码。

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class Solution {
public:
    string addStrings(string num1, string num2) {
        string ans;
        if(num1.size()>num2.size()) swap(num1, num2);
        reverse(num1.begin(), num1.end());
        reverse(num2.begin(), num2.end());
        int tmp = 0, minn = num1.size(), maxx = num2.size();
        for(int i = 0; i < minn; i ++){
            int x = num1[i]-'0', y = num2[i]-'0';
            int sum = x+y+tmp;
            if(sum>9){
                ans += sum%10+'0';
                tmp = sum/10;
            }
            else{
                ans += sum+'0';
                tmp = 0;
            }
        }
        for(int i = minn; i < maxx; i ++){
            int sum = num2[i]-'0'+tmp;
            if(sum>9){
                ans += sum%10+'0';
                tmp = sum/10;
            }
            else{
                ans += sum+'0';
                tmp = 0;
            }
        }
        if(tmp) ans += tmp+'0';
        reverse(ans.begin(), ans.end());
        // cout << ans << endl;
        return ans;
    }
};

class Solution {
public:
    int findMaxConsecutiveOnes(vector<int>& nums) {
        int ans = 0, cnt = 0;
        for(int i = 0; i < nums.size(); i ++){
            if(!nums[i]){
                ans = max(ans,cnt);
                cnt = 0;
            }
            else{
                cnt ++;
                if(i==nums.size()-1) ans = max(ans, cnt);
            }
        }
        return ans;
    }
};

class Solution {
public:
    int longestOnes(vector<int>& nums, int k) {
        int l = 0, r = 0;
        while(r<nums.size()){
            if(!nums[r++]) k --;
            if(k<0&&!nums[l++]) k ++;
        }
        return r-l;
    }
};

class Solution {
public:
    int solve(string s, int k, char op){
        int l = 0, r = 0;
        while(r<s.size()){
            if(s[r++]!=op) k --;
            if(k<0&&s[l++]!=op) k ++;
        }
        return r-l;
    }

    int maxConsecutiveAnswers(string answerKey, int k) {
        return max(solve(answerKey, k, 'T'), solve(answerKey, k, 'F'));
    }
};

class Solution {
public:
    ListNode* removeNthFromEnd(ListNode* head, int n) {
        int len = 0;
        ListNode* cur = head;
        while(cur){
            len ++;
            cur = cur->next;
        }
        //申请一个新的节点,节点值为0,且pre->next等于head
        ListNode* dummy = new ListNode(0, head);
        cur = dummy;
        for(int i = 1; i < len-n+1; i ++){
            cur = cur->next;
        }
        cur->next = cur->next->next;
        return dummy->next;
    }
};