Return the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.

Given a non-empty array of digits representing a non-negative integer, plus one to the integer.

Given a sorted linked list, delete all duplicates such that each element appear only once.

Given two binary strings, return their sum (also a binary string).

Given a string s consists of upper/lower-case alphabets and empty space characters ‘ ‘, return the length of last word in the string.

Compute and return the square root of x, where x is guaranteed to be a non-negative integer.

The count-and-say sequence is the sequence of integers with the first five terms as following:

Given an integer array nums, find the contiguous subarray (containing at least one number) which has the largest sum and return its sum.

给定两个由一些闭区间组成的列表，每个区间列表都是成对不相交的，并且已经排序。 返回这两个区间列表的交集。 形式上，闭区间 [a, b]（其中 a <= b）表示实数 x 的集合，而 a <= x <= b。两个闭区间的…

给出一个整数数组 A 和一个查询数组 queries。 对于第 i 次查询，有 val = queries[i][0], index = queries[i][1]，我们会把 val 加到 A[index] 上。然后，第 i 次查询的答案是 A 中偶数值的和。 （此处给定的 in…