Problem You are climbing a stair case. It takes n steps to reach to the top. Each time you can either climb 1 or 2 steps. In how many distinct ways can you climb to the top? Note: Given n will b...

Problem Implement int sqrt(int x). Compute and return the square root of x. x is guaranteed to be a non-negative integer. Example 1: Input: 4 Output: 2 Example 2: Input: 8 Output: 2 Explanat...

Problem Given two binary strings, return their sum (also a binary string). For example, a = “11” b = “1” Return “100”. 题目的意思就是按二进制的方式计算两个数相加。 Java 实现 package com.coderli.leetcode.algorithms...

Problem Given a non-negative integer represented as a non-empty array of digits, plus one to the integer. You may assume the integer do not contain any leading zero, except the number 0 itself. ...

Problem 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 w...

Problem Find the contiguous subarray within an array (containing at least one number) which has the largest sum. For example, given the array [-2,1,-3,4,-1,2,1,-5,4], the contiguous subarray [4,-...

Problem The count-and-say sequence is the sequence of integers with the first five terms as following: 1 11 21 1211 111221 1 is read off as “one 1” or 11. 11 is read off as “two 1s” ...

Problem Implement strStr(). Returns the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack. 题目其实就是实现Java中String的indexOf函数。因此，直接调用该方法，显然是不合适的。 Java 实现...

Problem Given an array and a value, remove all instances of that value in place and return the new length. Do not allocate extra space for another array, you must do this in place with constant m...

Problem Given a sorted array, remove the duplicates in place such that each element appear only once and return the new length. Do not allocate extra space for another array, you must do this in ...