07 2021 档案
摘要：Return the number of permutations of 1 to n so that prime numbers are at prime indices (1-indexed.) (Recall that an integer is prime if and only if it
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摘要：You have an infinite number of stacks arranged in a row and numbered (left to right) from 0, each of the stacks has the same maximum capacity. Impleme
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摘要：Given the head of a linked list, we repeatedly delete consecutive sequences of nodes that sum to 0 until there are no such sequences. After doing so,
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摘要：Let the function f(s) be the frequency of the lexicographically smallest character in a non-empty string s. For example, if s = "dcce" then f(s) = 2 b
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摘要：A transaction is possibly invalid if: the amount exceeds $1000, or; if it occurs within (and including) 60 minutes of another transaction with the sam
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摘要：Given a string s, return the last substring of s in lexicographical order. Example 1: Input: s = "abab" Output: "bab" Explanation: The substrings are
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摘要：Given an n x n grid containing only values 0 and 1, where 0 represents water and 1 represents land, find a water cell such that its distance to the ne
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摘要：Given the root of a binary tree, the level of its root is 1, the level of its children is 2, and so on. Return the smallest level x such that the sum
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摘要：You are given an array of strings words and a string chars. A string is good if it can be formed by characters from chars (each character can only be
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摘要：Design a data structure that efficiently finds the majority element of a given subarray. The majority element of a subarray is an element that occurs
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摘要：Given a string text, we are allowed to swap two of the characters in the string. Find the length of the longest substring with repeated characters. Ex
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摘要：You have d dice and each die has f faces numbered 1, 2, ..., f. Return the number of possible ways (out of fd total ways) modulo 109 + 7 to roll the d
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摘要：Given a string date representing a Gregorian calendar date formatted as YYYY-MM-DD, return the day number of the year. Example 1: Input: date = "2019-
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摘要：You are given a string text. You should split it to k substrings (subtext1, subtext2, ..., subtextk) such that: subtexti is a non-empty string. The co
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