摘要：Given an integer matrix, find the length of the longest increasing path. From each cell, you can either move to four directions: left, right, up or do 阅读全文

摘要：Remove the minimum number of invalid parentheses in order to make the input string valid. Return all possible results. Note: The input string may cont 阅读全文

摘要：Given a binary tree and a sum, find all root-to-leaf paths where each path's sum equals the given sum. Note: A leaf is a node with no children. Exampl 阅读全文