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[leetcode 437] Path Sum III You are given a binary tree in which each node contains an integer value. Find the number of paths that sum to a given value. The path does not need to start or end at the root or a leaf, but it must go downwards (traveling only from parent nodes to child nodes). The tree has no more than 1,000 nodes and the values are in the range -1,000,000 to 1,000,000. Example: root = [10,5,-3,3,2,null,11,3,.. 2020. 10. 18.
[leetcode 394] Decode String Given an encoded string, return its decoded string. The encoding rule is: k[encoded_string], where the encoded_string inside the square brackets is being repeated exactly k times. Note that k is guaranteed to be a positive integer. You may assume that the input string is always valid; No extra white spaces, square brackets are well-formed, etc. Furthermore, you may assume that the original data .. 2020. 10. 18.
[leetcode 347] Top K Frequent Elements Given a non-empty array of integers, return the k most frequent elements. 주어진 배열에서 가장 자주 등장하는 요소 k번째까지 리턴하기 Example 1: Input: nums = [1,1,1,2,2,3], k = 2 Output: [1,2] Example 2: Input: nums = [1], k = 1 Output: [1] Note: You may assume k is always valid, 1 ≤ k ≤ number of unique elements. Your algorithm's time complexity must be better than O(n log n), where n is the array's size. It's guarante.. 2020. 10. 18.
[leetcode 32] Longest Valid Parentheses Given a string containing just the characters '(' and ')', find the length of the longest valid (well-formed) parentheses substring. 가장 긴 well formed parentheses 찾기 Example 1: Input: s = "(()" Output: 2 Explanation: The longest valid parentheses substring is "()". Example 2: Input: s = ")()())" Output: 4 Explanation: The longest valid parentheses substring is "()()". Example 3: Input: s = "" Out.. 2020. 10. 17.

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