摘要：
There is an m by n grid with a ball. Given the start coordinate (i,j) of the ball, you can move the ball to adjacent cell or cross the grid boundary i 阅读全文
摘要：
Given two words word1 and word2, find the minimum number of steps required to make word1 and word2 the same, where in each step you can delete one cha 阅读全文