For this question, we need to consider a case when word A and word B bot...

This problem can be simplified to an n shortest distance problem. We sta...

This question is actually asking how to check whether a graph has a cycl...

For each node, there may be several conditions: 1. root.left <0 and root...

For this problem, we divide it into 2 parts, reverse LinkedList and conn...

For this problem, we take use of the sliding window. First we should sea...

We divide the number every 4 digits, for each interval, it's xxx hundred...

For this problem, we can scan all the people in one-pass. From people 0,...

For LRU cache, it's like a fifo queue but reassign the existing value to...