西雅图打卡

1052. Grumpy Bookstore Owner
Problem: Return the maximum number of customers that can be satisfied throughout the day.
Solution: Sliding Window

991. Broken Calculator
Problem: Return the minimum number of operations needed to display the number Y.
Solution: Greedy (judged by two conditions: even and odd)

564. Find the Closest Palindrome
Problem: Given an integer n, find the closest integer (not including itself), which is a palindrome.
Solution: Math, there are 3 conditions to make Palindrome

403. Frog Jump
Problem: Given a list of stones' positions (in units) in sorted ascending order, determine if the frog is able to cross the river by landing on the last stone.
Solution: DP(AC), DFS(TLE)

713. Subarray Product Less Than K
Problem: Your are given an array of positive integers nums. Count and print the number of (contiguous) subarrays where the product of all the elements in the subarray is less than k.
Solution: Sliding window
凡是求subarray小于或等于K的，都跟Sliding window可以联系上

103. Binary Tree Zigzag Level Order Traversal
Problem: Given a binary tree, return the zigzag level order traversal of its nodes' values.
Solution: queue+q.size() vector

1072. Flip Columns For Maximum Number of Equal Rows
Problem: Return the maximum number of rows that have all values equal after some number of flips.
Solution: Find patterns of each row (xor same)

1260. Shift 2D Grid
Problem: Given a 2D grid of size n * m and an integer k. You need to shift the grid k times.
Solution: 计算shift后各个元素最后出现位置

1261. Find Elements in a Contaminated Binary Tree
Problem: Given a binary tree with the following rules
Solution: use set

1268. Search Suggestions System
Problem: Given an array of strings products and a string searchWord.
Solution: 不用Trie，直接排序后找出当前输入字符串最匹配的那个，连续取三个，亚麻OA好像也出现过的样子

1267. Count Servers that Communicate
Problem: Return the number of servers that communicate with any other server.
Solution: 统计columns和rows是否存在1，(m+n)，然后m*n判断为1时行列是否存在1.

1114. Print in Order
Problem: Design a mechanism and modify the program to ensure that second() is executed after first(), and third() is executed after second().
Solution: multithreading, c++用的是condition variable判断和唤醒

1266. Minimum Time Visiting All Points
Problem: Your task is to find the minimum time in seconds to visit all points.
Solution: 可横，竖，斜着走，所以直接判断max(横，竖)