Hans的博客

解释：上面是由数组 [0,1,0,2,1,0,1,3,2,1,2,1] 表示的高度图，在这种情况下，可以接 6 个单位的雨水（蓝色部分表示雨水）。给定 n 个非负整数表示每个宽度为 1 的柱子的高度图，计算按此排列的柱子，下雨之后能接多少雨水。输入：height = [0,1,0,2,1,0,1,3,2,1,2,1]输入：height = [4,2,0,3,2,5]...

给你一个字符串 s 、一个字符串 t。返回 s 中涵盖 t 所有字符的最小子串。如果 s 中不存在涵盖 t 所有字符的子串，则返回空字符串 ""。对于 t 中重复字符，我们寻找的子字符串中该字符数量必须不少于 t 中该字符数量。输入：s = "ADOBECODEBANC", t = "ABC"解释: t 中两个字符 'a' 均应包含在 s 的子串中，如果 s 中存在这样的子串，我们保证它是唯一的答案。输入: s = "a", t = "aa"输入：s = "a", t = "a"...

class Solution {public: typedef vector<vector<long>> vvl; vvl multiply(vvl& a,vvl& b){ vvl c={{1,0},{0,1}}; for(int i=0;i<2;i++){ for(int j=0;j<2;j++){ c[i][j]=(a[i][...

方法一：哈希表，需要额外空间class Solution {public: int singleNumber(vector<int>& nums) { unordered_map<int,int> hash_map; for(auto& num:nums){ hash_map[num]++; } for(auto& [val,count]:hash_ma..

方法一：bitset容器class Solution {public: vector<int> countBits(int n) { vector<int> ans; for(int i=0;i<=n;i++){ bitset<32> bs(i); ans.push_back((int)bs.count()); } return ans..

class Solution {public: string addBinary(string a, string b) { int idx_a=a.size()-1,idx_b=b.size()-1; string ans=""; int carry=0;//进位初始化为0 while(idx_a>=0||idx_b>=0||carry!=0){ int sum=carry; ...

提示:-231<= a, b <= 231- 1 b != 0class Solution {public: int divide(int a, int b) { bool sign=(a^b)>>31;//判断a和b是否异号，右移31位到符号位 long dividend=abs((long)a),divisor=abs((long)b);//转为正数 long ans=0; while(d...

On an n x n chessboard, a knight starts at the cell (row, column) and attempts to make exactly k moves. The rows and columns are 0-indexed, so the top-left cell is (0, 0), and the bottom-right cell is (n - 1, n - 1).A chess knight has eight possible move

You are given an array pairs, where pairs[i] = [xi, yi], and:There are no duplicates.xi < yiLet ways be the number of rooted trees that satisfy the following conditions:The tree consists of nodes whose values appeared in pairs.A pair [xi, yi] exi

Serialization is the process of converting a data structure or object into a sequence of bits so that it can be stored in a file or memory buffer, or transmitted across a network connection link to be reconstructed later in the same or another computer env

Given a binary tree, find the lowest common ancestor (LCA) of two given nodes in the tree.According to the definition of LCA on Wikipedia: “The lowest common ancestor is defined between two nodes p and q as the lowest node in T that has both p and q as d

You are given a perfect binary tree where all leaves are on the same level, and every parent has two children. The binary tree has the following definition:struct Node { int val; Node *left; Node *right; Node *next;}Populate each next pointer t...

Given two integer arrays preorder and inorder where preorder is the preorder traversal of a binary tree and inorder is the inorder traversal of the same tree, construct and return the binary tree.Constraints:1 <= preorder.length <= 3000inorder.l

Given two integer arrays inorder and postorder where inorder is the inorder traversal of a binary tree and postorder is the postorder traversal of the same tree, construct and return the binary tree.Constraints:1 <= inorder.length <= 3000posto

You are given an m x n binary matrix grid, where 0 represents a sea cell and 1 represents a land cell.A move consists of walking from one land cell to another adjacent (4-directionally) land cell or walking off the boundary of the grid.Return the numbe

You are given a 0-indexed integer array nums, where nums[i] represents the score of the ith student. You are also given an integer k.Pick the scores of any k students from the array so that the difference between the highest and the lowest of the k score

Given an integer array nums and an integer k, return the number of pairs (i, j) where i < j such that |nums[i] - nums[j]| == k.The value of |x| is defined as:x if x >= 0.-x if x < 0.Constraints:1 <= nums.length <= 200 1 <= num

A string s is called happy if it satisfies the following conditions:s only contains the letters 'a', 'b', and 'c'.s does not contain any of "aaa", "bbb", or "ccc" as a substring.s contains at most a occurrences of the letter 'a'.s contains at most b o

You are given an integer array nums. The unique elements of an array are the elements that appear exactly once in the array.Return the sum of all the unique elements of nums.Constraints:1 <= nums.length <= 100 1 <= nums[i] <= 100clas

In a gold mine grid of size m x n, each cell in this mine has an integer representing the amount of gold in that cell, 0 if it is empty.Return the maximum amount of gold you can collect under the conditions:Every time you are located in a cell you will

Given an integer k, return the minimum number of Fibonacci numbers whose sum is equal to k. The same Fibonacci number can be used multiple times.The Fibonacci numbers are defined as:F1 = 1F2 = 1Fn = Fn-1 + Fn-2 for n > 2.It is guaranteed that for

Given a m * n matrix seats that represent seats distributions in a classroom. If a seat is broken, it is denoted by '#' character otherwise it is denoted by a '.' character.Students can see the answers of those sitting next to the left, right, upper left

C++位运算可以提高运算效率移位：用x<<1代替x*2；x>>1代替x/2位与：取余运算x%n可用x&(n-1)代替

Given an array nums and a value val, remove all instances of that value in-place and return the new length.Do not allocate extra space for another array, you must do this by modifying the input array in-place with O(1) extra memory.The order of element