题目描述: Given an integer (signed 32 bits), write a function to check whether it is a power of 4. Example:Given num = 16, return true. Given num = 5, return false. 解题思路: 位操作. 首先判断是不是只有一位数字为1,其余为0 然后判断为1的位置是不是奇数位 代码如下: class Solution(object): def isPower…
原题地址:https://oj.leetcode.com/problems/length-of-last-word/ 题意: Given a string s consists of upper/lower-case alphabets and empty space characters ' ', return the length of last word in the string. If the last word does not exist, return 0. Note: A wo…
原题地址:https://oj.leetcode.com/problems/evaluate-reverse-polish-notation/ 题意: Evaluate the value of an arithmetic expression in Reverse Polish Notation. Valid operators are +, -, *, /. Each operand may be an integer or another expression. Some examples…