Leetcode860.柠檬水找零

文章链接 ：代码随想录
题目链接：860.柠檬水找零

class Solution {
public:bool lemonadeChange(vector<int>& bills) {int five = 0, ten = 0, twenty = 0;for (int i = 0; i < bills.size(); i++){if (bills[i] == 5) five++;if (bills[i] == 10) {five--;ten++;}if (bills[i] == 20){if (ten > 0){ten--;five--;}else{five -= 3;}}if (five < 0 || ten < 0) return false;}return true;}
};

Leetcode406.根据身高重建队列

文章链接：代码随想录
题目链接：406.根据身高重建队列

使用vector，insert时可能发生扩容拷贝，费时

class Solution {
public:static bool cmp(vector<int>& a, vector<int>& b){if (a[0] == b[0]) return a[1] < b[1];return a[0] > b[0];}vector<vector<int>> reconstructQueue(vector<vector<int>>& people) {sort(people.begin(), people.end(), cmp);vector<vector<int>> que;for (int i = 0; i < people.size(); i++){int position = people[i][1];que.insert(que.begin() + position, people[i]);}return que;}
};

使用链表，效率比vector快

class Solution {
public:static bool cmp(vector<int>& a, vector<int>& b){if (a[0] == b[0]) return a[1] < b[1];return a[0] > b[0];}vector<vector<int>> reconstructQueue(vector<vector<int>>& people) {sort(people.begin(), people.end(), cmp);list<vector<int>> que;for (int i = 0; i < people.size(); i++){int position = people[i][1];auto it = que.begin();while(position--) it++;que.insert(it, people[i]);}return vector<vector<int>>(que.begin(), que.end());}
};

Leetcode452. 用最少数量的箭引爆气球

文章链接：代码随想录
题目链接：452. 用最少数量的箭引爆气球

区间问题，注意如何排序和更新xend。

class Solution {
public:static bool cmp(vector<int>& a, vector<int>& b){if (a[0] == b[0]) return a[1] < b[1];return a[0] < b[0];}int findMinArrowShots(vector<vector<int>>& points) {sort(points.begin(), points.end(), cmp);int result = 1;for (int i = 1; i < points.size(); i++){if (points[i][0] > points[i - 1][1]) result++;else{points[i][1] = min(points[i - 1][1], points[i][1]);}}return result;}
};

第三十五天打卡，今天猛学操作系统，加油！！！