随笔分类 - leetcode
摘要：Given an integer array with all positive numbers and no duplicates, find the number of possible combinations that add up to a positive integer target.
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摘要：A sequence of numbers is called a wiggle sequence if the differences between successive numbers strictly alternate between positive and negative. The
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摘要：Given a non-negative integer n, count all numbers with unique digits, x, where 0 ≤ x < 10n. Example: Input: 2 Output: 91 Explanation: The answer shoul
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摘要：Given a 2D matrix matrix, find the sum of the elements inside the rectangle defined by its upper left corner (row1, col1) and lower right corner (row2
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摘要：Given a positive integer n, find the least number of perfect square numbers (for example, 1, 4, 9, 16, ...) which sum to n. Example 1: Input: n = 12 O
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摘要：You are given coins of different denominations and a total amount of money amount. Write a function to compute the fewest number of coins that you nee
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摘要：Write a program to find the n-th ugly number. Ugly numbers are positive numbers whose prime factors only include 2, 3, 5. Example: Input: n = 10 Outpu
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摘要：Given a 2D binary matrix filled with 0's and 1's, find the largest square containing only 1's and return its area. Example: Input: 1 0 1 0 0 1 0 1 1 1
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摘要：Given a string containing just the characters '(' and ')', find the length of the longest valid (well-formed) parentheses substring. Example 1: Input:
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摘要：On a staircase, the i-th step has some non-negative cost cost[i] assigned (0 indexed). Once you pay the cost, you can either climb one or two steps. Y
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摘要：Given a string s and a string t, check if s is subsequence of t. You may assume that there is only lower case English letters in both s and t. t is po
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摘要：Given an integer array nums, find the sum of the elements between indices i and j (i ≤ j), inclusive. Example: Given nums = [-2, 0, 3, -5, 2, -1] sumR
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摘要：You are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed, the only constraint stopping yo
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摘要：Given a non-empty string s and a dictionary wordDict containing a list of non-empty words, determine if s can be segmented into a space-separated sequ
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摘要：Given a binary tree, return all root-to-leaf paths. Note: A leaf is a node with no children. Example: Input: 1 / \ 2 3 \ 5 Output: ["1->2->5", "1->3"]
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摘要：Given a binary search tree, write a function kthSmallest to find the kth smallest element in it. Note:You may assume k is always valid, 1 ≤ k ≤ BST's
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摘要：Given n, how many structurally unique BST's (binary search trees) that store values 1 ... n? Example: Input: 3 Output: 5 Explanation: Given n = 3, the
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摘要：You need to find the largest value in each row of a binary tree. Example: Input: 1 / \ 3 2 / \ \ 5 3 9 Output: [1, 3, 9] # Definition for a binary tre
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摘要：Given a binary tree, find the leftmost value in the last row of the tree. Example 1: Input: 2 / \ 1 3 Output: 1 Example 2: Input: 1 / \ 2 3 / / \ 4 5
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摘要：Find the sum of all left leaves in a given binary tree. Example: 3 / \ 9 20 / \ 15 7 There are two left leaves in the binary tree, with values 9 and 1
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