摘要：Given the root of a binary tree, return the sum of values of nodes with an even-valued grandparent. If there are no nodes with an even-valued grandpar 阅读全文

摘要：Given a m x n matrix mat and an integer k, return a matrix answer where each answer[i][j] is the sum of all elements mat[r][c] for: i - k <= r <= i + 阅读全文

摘要：We are given a list nums of integers representing a list compressed with run-length encoding. Consider each adjacent pair of elements [freq, val] = [n 阅读全文

摘要：Given a string s. In one step you can insert any character at any index of the string. Return the minimum number of steps to make s palindrome. A Pali 阅读全文