A message containing letters from A-Z is being encoded to numbers using the following mapping way: 'A' -> 1 'B' -> 2 ... 'Z' -> 26 Beyond that, now the encoded string can also contain the character '*', which can be treated as one of the numbers…
A robot is located at the top-left corner of a m x n grid (marked 'Start' in the diagram below). The robot can only move either down or right at any point in time. The robot is trying to reach the bottom-right corner of the grid (marked 'Finish' in t…
Given n, how many structurally unique BST's (binary search trees) that store values 1...n? For example, Given n = 3, there are a total of 5 unique BST's. 1 3 3 2 1 \ / / / \ \ 3 2 1 1 3 2 / / \ \ 2 1 2 3 法I:后序遍历.同Unique Binary Search Trees II,只是现在…
1381 - Scientific Experiment Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://www.lightoj.com/volume_showproblem.php?problem=1381 Description John wants to be a scientist. A first step of becoming a scientist is to perform experiment. John has de…