刷题记录贴

K Closest Points to Origin

priority queue, sort, divide and conquer
这一题需要跟海量数据处理课上的方法结合起来看 (tbc)

Valid Palindrome

跳过非字母char 比较时注意判断大小写

Valid Palindrome II

递归解法 即从外向内走 如果出现非palindrom的情况 即start或end必须去掉一个 此时遍历start+1. end 以及start, end-1两个子字符串 如果两个都不为palindrome则return false

递归一直是弱项 一开始思路完全不对 #revisit

06/05
1. Longest Palindromic Substring
2. Longest Palindromic Subsequence
3. Integer to English Words
4. Add Binary
5. Course Schedule
6. Alien Dictionary

7. 28. Implement strStr()

06/22:
1. https://www.lintcode.com/problem/can-reach-the-endpoint/
2. https://www.lintcode.com/problem/friend-circles/ : 用BFS写的, todo: 用并查集写

task scheduler: https://leetcode.com/problems/task-scheduler/
1. thoughts: 排列组合题目,

2. dry run
3. test case (input check)
4. time complexity / space complexity
5. 遗漏点
6. 如果需要revisit加#revisit

task scheduler: https://leetcode.com/problems/task-scheduler/
1. 思路: 排列组合, 把结果拆解成running time + idle time, idle time的最大值是task里frequency最大值所需要的idle间隔, iterate, decrease idle time by min(fmax-1, f). 最后取idletime为non-negative, return sum
2. dry run
3. test case (input check)
4. time complexity / space complexity
5. 遗漏点
6. 如果需要revisit加#revisit

three sum: https://leetcode.com/problems/3sum/
sort, 抓住一个元素 然后以此为基准对右侧元素two sum

task scheduler: https://leetcode.com/problems/task-scheduler/
排列组合题, 结果 = time unit + idle time, idle time 由最高频的task算出基础值然后在上面看能不能被别的task占据idle time值