水中的鱼

Design a stack that supports push, pop, top, and retrieving the minimum element in constant time. push(x) -- Push element x onto stack. ...

A peak element is an element that is greater than its neighbors. Given an input array where  num[i] ≠ num[i+1] , find a peak element and ...

Given two integers representing the numerator and denominator of a fraction, return the fraction in string format. If the fractional part...

Given a 2d grid map of  '1' s (land) and  '0' s (water), count the number of islands. An island is surrounded by water and ...

Implement a basic calculator to evaluate a simple expression string. The expression string may contain open  (  and closing parentheses  ...

Given a sorted integer array without duplicates, return the summary of its ranges. For example, given  [0,1,2,4,5,7] , return  ["0-...

Write an efficient algorithm that searches for a value in an  m  x  n  matrix. This matrix has the following properties: Integers in ea...