2016 年 11月 30 日随笔档案 - neverlandly

2016年11月30日

摘要： Three types of answer: Map Solution, O(N) memory, O(N) init, O(1) pick. Like @dettier's Reservoir Sampling. O(1) init, O(1) memory, but O(N) to pick. 阅读全文

posted @ 2016-11-30 12:23 neverlandly 阅读(410) 评论(0) 推荐(0)

Leetcode: Sum of Left Leaves

摘要： Recursion: 是不是left子数完全由bottom往上第二层决定，如果是left子树且是叶子节点，那么就是left leaves, parent得告诉child是不是在left子树 BFS: 阅读全文

posted @ 2016-11-30 11:45 neverlandly 阅读(370) 评论(0) 推荐(0)

Leetcode: Is Subsequence

摘要： Basic Solution: DP, O(mn) time, O(m) space, m is the size of s, n is the size of t Greedy Solution: O(n) time, O(1) space Follow Up: The best solution 阅读全文

posted @ 2016-11-30 11:09 neverlandly 阅读(1189) 评论(0) 推荐(0)

Leetcode: Elimination Game

摘要： refer to https://discuss.leetcode.com/topic/59293/java-easiest-solution-o-logn-with-explanation Time Complexity: O(log n) update and record head in ea 阅读全文

posted @ 2016-11-30 06:52 neverlandly 阅读(360) 评论(0) 推荐(0)

Leetcode: Find the Difference

摘要： O（N）time, O(1) space 阅读全文

posted @ 2016-11-30 05:40 neverlandly 阅读(251) 评论(0) 推荐(0)

Leetcode: Longest Absolute File Path

摘要： Time Complexity: O(N) The depth of the directory/file is calculated by counting how many "\t"s are there.The time complexity is O(n) because each subs 阅读全文

posted @ 2016-11-30 05:19 neverlandly 阅读(362) 评论(0) 推荐(0)

Leetcode: Mini Parser

摘要：有括号这种一般要用stack, stack top 就是当前着眼的那一个NestedInteger, 可以对其添加新的元素。注意47行判断很关键，顺带处理了 "[]," 括号后面是逗号的情况阅读全文

posted @ 2016-11-30 02:28 neverlandly 阅读(379) 评论(0) 推荐(0)