Problem statement Given a positive integer a, find the smallest positive integer b whose multiplication of each digit equals to a. If there is no answer or the answer is not fit in 32-bit signed integer, then return 0. Example 1Input: 48 Output: 68 E…

[LeetCode]Minimum Depth of Binary Tree Given a binary tree, find its minimum depth. The minimum depth is the number of nodes along the shortest path from the root node down to the nearest leaf node. 递归和非递归,此提比较简单.广度优先遍历即可.关键之处就在于如何保持访问深度. 下面是4种代码: im…

Leetcode Find Minimum in Rotated Sorted Array 题目大意: 对一个有序数组翻转, 就是随机取前K个数,移动到数组的后面,然后让你找出最小的那个数.注意,K有可能是0,也就是没有翻转. 毫无疑问,遍历一次肯定能够找到,但这样时间复杂度是O(n).假设你在面试的时候遇到这种问题,你这样回答面试官肯定不会惬意的.我们接下来讨论有没有什么更快的方法.O(nlogn)?? 我还是把O(N)的代码贴出来,不知道为什么leetcode上竟然不超时. //O(n) c…

Leetcode 931. Minimum falling path sum 最小下降路径和(动态规划) 题目描述 已知一个正方形二维数组A,我们想找到一条最小下降路径的和 所谓下降路径是指,从一行到下一行,只能选择间距不超过1的列(也就是说第一行的第一列,只能选择第二行的第一列和第二列:第二行的第二列,只能选择第三行的第一列第二列第三列),最小下降路径就是这个路径的和最小 测试样例 Input: [[1,2,3],[4,5,6],[7,8,9]] Output: 12 Explanation:…

Given strings S and T, find the minimum (contiguous) substring W of S, so that T is a subsequenceof W. If there is no such window in S that covers all characters in T, return the empty string "". If there are multiple such minimum-length windows…

Given a positive integer a, find the smallest positive integer b whose multiplication of each digit equals to a. If there is no answer or the answer is not fit in 32-bit signed integer, then return 0. Example 1Input: 48 Output: 68 Example 2Input: 15…

Follow up for "Find Minimum in Rotated Sorted Array":What if duplicates are allowed? Would this affect the run-time complexity? How and why? Suppose a sorted array is rotated at some pivot unknown to you beforehand. (i.e., 0 1 2 4 5 6 7 might be…

Suppose a sorted array is rotated at some pivot unknown to you beforehand. (i.e., 0 1 2 4 5 6 7 might become 4 5 6 7 0 1 2). Find the minimum element. You may assume no duplicate exists in the array. 这道寻找旋转有序数组的最小值肯定不能通过直接遍历整个数组来寻找,这个方法过于简单粗暴,这样的话,旋不…

原题链接在这里:https://leetcode.com/problems/find-minimum-in-rotated-sorted-array-ii/ 题目: Follow up for "Find Minimum in Rotated Sorted Array":What if duplicates are allowed? Would this affect the run-time complexity? How and why? Suppose a sorted arra…

原题链接在这里:https://leetcode.com/problems/find-minimum-in-rotated-sorted-array/ Method 1 就是找到第一个违反升序的值,就是最小值,若是没有,那么第一个值就是最小值. Time O(n). Method 2 Binary Search. 与Find Peak Element类似. while 的条件是 l < r 并且 nums[l] > nums[r], 不然 l 到 r 这一段就是sorted的. nums[mi…

Given a string S and a string T, find the minimum window in S which will contain all the characters in T in complexity O(n). For example,S = "ADOBECODEBANC"T = "ABC" Minimum window is "BANC". Note:If there is no such window i…

For a undirected graph with tree characteristics, we can choose any node as the root. The result graph is then a rooted tree. Among all possible rooted trees, those with minimum height are called minimum height trees (MHTs). Given such a graph, write…

Given a binary search tree with non-negative values, find the minimum absolute difference between values of any two nodes. Example: Input: 1 \ 3 / 2 Output: 1 Explanation: The minimum absolute difference is 1, which is the difference between 2 and 1…

Given a binary tree, find its minimum depth. The minimum depth is the number of nodes along the shortest path from the root node down to the nearest leaf node. 题目标题:Tree 这道题目给了我们一个二叉树,让我们找到它最小的深度,注意这里的最小深度是指root 到一个 leaf node. 举个例子: 1 /   2 / 3 这种情况,…

Given a non-empty special binary tree consisting of nodes with the non-negative value, where each node in this tree has exactly two or zero sub-node. If the node has two sub-nodes, then this node's value is the smaller value among its two sub-nodes.…

[Leetcode] Maximum and Minimum Depth of Binary Tree 二叉树的最小最大深度 (最小有3种解法) 描述 解析 递归深度优先搜索 当求最大深度时,我们只要在左右子树中取较大的就行了. 然而最小深度时,如果左右子树中有一个为空会返回0,这时我们是不能算做有效深度的. 所以分成了三种情况,左子树为空,右子树为空,左右子树都不为空.当然,如果左右子树都为空的话,就会返回1. 广度优先搜索(类似层序遍历的思想) 递归解法本质是深度优先搜索,但因为我们是求最小…

    题目URL:https://leetcode.com/problems/minimum-depth-of-binary-tree/ 111. Minimum Depth of Binary Tree My Submissions Question Total Accepted: 94580 Total Submissions: 312802 Difficulty: Easy Given a binary tree, find its minimum depth. The minimum…

Minimum Time Difference 题解 原创文章,拒绝转载 题目来源:https://leetcode.com/problems/minimum-time-difference/description/ Description Given a list of 24-hour clock time points in "Hour:Minutes" format, find the minimum minutes difference between any two time…

Minimum Path Sum 题解 原创文章,拒绝转载 题目来源:https://leetcode.com/problems/minimum-path-sum/description/ Description Given a m x n grid filled with non-negative numbers, find a path from top left to bottom right which minimizes the sum of all numbers along its…

原题链接在这里:https://leetcode.com/problems/second-minimum-node-in-a-binary-tree/description/ 题目: Given a non-empty special binary tree consisting of nodes with the non-negative value, where each node in this tree has exactly two or zero sub-node. If the n…

Given a string S of '(' and ')' parentheses, we add the minimum number of parentheses ( '(' or ')', and in any positions ) so that the resulting parentheses string is valid. Formally, a parentheses string is valid if and only if: It is the empty stri…

There are N workers.  The i-th worker has a quality[i] and a minimum wage expectation wage[i]. Now we want to hire exactly K workers to form a paid group.  When hiring a group of K workers, we must pay them according to the following rules: Every wor…

Given strings S and T, find the minimum (contiguous) substring W of S, so that T is a subsequence of W. If there is no such window in S that covers all characters in T, return the empty string "". If there are multiple such minimum-length window…

Given an array of n positive integers and a positive integer s, find the minimal length of a contiguous subarray of which the sum ≥ s. If there isn't one, return 0 instead. Example: Input: s = 7, nums = [2,3,1,2,4,3] Output: 2 Explanation: the subarr…

Given a string S and a string T, find the minimum window in S which will contain all the characters in T in complexity O(n). Example: Input: S = "ADOBECODEBANC", T = "ABC" Output: "BANC" Note: If there is no such window in S…

原题链接在这里:https://leetcode.com/problems/minimum-remove-to-make-valid-parentheses/ 题目: Given a string s of '(' , ')' and lowercase English characters. Your task is to remove the minimum number of parentheses ( '(' or ')', in any positions ) so that the…

原题链接在这里:https://leetcode.com/problems/minimum-knight-moves/ 题目: In an infinite chess board with coordinates from -infinity to +infinity, you have a knight at square [0, 0]. A knight has 8 possible moves it can make, as illustrated below. Each move is…

原题链接在这里:https://leetcode.com/problems/minimum-score-triangulation-of-polygon/ 题目: Given N, consider a convex N-sided polygon with vertices labelled A[0], A[i], ..., A[N-1] in clockwise order. Suppose you triangulate the polygon into N-2 triangles.  F…

原题链接在这里:https://leetcode.com/problems/minimum-swaps-to-make-sequences-increasing/ 题目: We have two integer sequences A and B of the same non-zero length. We are allowed to swap elements A[i] and B[i].  Note that both elements are in the same index pos…

原题链接在这里:https://leetcode.com/problems/minimum-cost-to-merge-stones/ 题目: There are N piles of stones arranged in a row.  The i-th pile has stones[i] stones. A move consists of merging exactly K consecutive piles into one pile, and the cost of this mov…