標籤:1 題目Given a string containing just the characters ‘(‘, ‘)‘, ‘{‘, ‘}‘, ‘[‘ and ‘]‘, determine if the input string is valid.The brackets must close in the correct order, "()" and "()[]{}" are
標籤:Problem: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: ["2", "1", "+", "3", "*"] -> ((2 + 1
標籤:Problem:Given two integers representing the numerator and denominator of a fraction, return the fraction in string format.If the fractional part is repeating, enclose the repeating part in parentheses.For example,Given numerator = 1, denominator =
標籤:Given a string, find the length of the longest substring without repeating characters. For example, the longest substring without repeating letters for "abcabcbb" is "abc", which the length is 3. For "bbbbb" the longest substring is "b", with the
標籤:For a given sorted array (ascending order) and a target number, find the first index of this number in O(log n) time complexity.If the target number does not exist in the array, return -1. Have you met this question in a real
標籤:Given an array of n positive integers and a positive integer s, find the minimal length of a subarray of which the sum ≥ s. If there isn‘t one, return 0 instead.For example, given the