西雅图打卡

1192. Critical Connections in a Network
Problem: Return all critical connections in the network in any order.
Solution: Tajan algorithm
其实也就是找SCC

957. Prison Cells After N Days
Problem: Given the initial state of the prison, return the state of the prison after N days (and N such changes described above.)
Solution: MOD 14

635. Design Log Storage System
Problem: Return the id of logs whose timestamps are within the range from start to end.
Solution: hash + compare by keyword

780. Reaching Points
Problem: Given a starting point (sx, sy) and a target point (tx, ty), return True if and only if a sequence of moves exists to transform the point (sx, sy) to (tx, ty). Otherwise, return False.
Solution: 反过来找，通过modulo找到(x, kx+y) or (ky+x, y) 再进行判断，O(log(n))

256. Paint House
Problem: Find the minimum cost to paint all houses.
Solution: DP

920. Number of Music Playlists
Problem: Return the number of possible playlists.  
Solution: DP, combinations

945. Minimum Increment to Make Array Unique
Problem:Return the least number of moves to make every value in A unique.
Solution:Sort or Count

739. Daily Temperatures
Problem: Given a list of daily temperatures T, return a list such that, for each day in the input, tells you how many days you would have to wait until a warmer temperature. If there is no future day for which this is possible, put 0 instead.
Solution: Monotonous stack

上周的Contest
1247. Minimum Swaps to Make Strings Equal
Problem: Return the minimum number of swaps required to make s1 and s2 equal, or return -1 if it is impossible to do so.
Solution: 统计两字符串同一位置(x,y)和(y,x)数目，两个分别除以2后得到至少要交换的次数，再判断%2是否都为1，是则再加2。其余情况都为-1

1248. Count Number of Nice Subarrays
Problem: Given an array of integers nums and an integer k. A subarray is called nice if there are k odd numbers on it.
Return the number of nice sub-arrays.
Solution: sliding window, 统计恰好为K可以变成至多为K减去至多为K-1.

University Career Fair (Twitter)
Problem: Given each company's start time and durations, return the maximum events can be held in the university.
Solution: Interval scheduling (Greedy)