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添加二进制题
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‎数据结构篇/二进制.md‎

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JS二进制基础知识： [二进制](https://wangdoc.com/javascript/operators/bit.html)
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##### 136.只出现一次的数字 [single-number](https://leetcode-cn.com/problems/single-number/)
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##### [136.只出现一次的数字](https://leetcode-cn.com/problems/single-number/)
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给定一个**非空**整数数组，除了某个元素只出现一次以外，其余每个元素均出现两次。找出那个只出现了一次的元素。
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};
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```
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##### 137.只出现一次的数字 II [single-number-ii](https://leetcode-cn.com/problems/single-number-ii/)
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##### [137.只出现一次的数字 II](https://leetcode-cn.com/problems/single-number-ii/)
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给定一个**非空**整数数组，除了某个元素只出现一次以外，其余每个元素均出现了三次。找出那个只出现了一次的元素。
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};
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```
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##### [260. 只出现一次的数字 III](https://leetcode-cn.com/problems/single-number-iii/)
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```js
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/*
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* 执行用时：560 ms, 在所有 JavaScript 提交中击败了8.67%的用户 😂，indexof这么耗时
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* 内存消耗：38.4 MB, 在所有 JavaScript 提交中击败了91.67%的用户
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*/
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var singleNumber = function (nums) {
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const res = []
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nums.forEach(num => {
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if (nums.indexOf(num) === nums.lastIndexOf(num)) {
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res.push(num)
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}
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})
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return res
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};
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```
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```js
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var singleNumber = function (nums) {
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let ret = 0;
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for (let n of nums) {
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ret ^= n;
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}
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let div = 1;
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while ((div & ret) === 0) {
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div <<= 1;
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}
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let a = 0, b = 0;
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for (let n of nums) {
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if ((div & n) !== 0) {
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a ^= n;
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} else {
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b ^= n;
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}
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}
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return [a, b];
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}
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```
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##### [191. 位1的个数](https://leetcode-cn.com/problems/number-of-1-bits/)
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```js
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var hammingWeight = function(n) {
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let res = 0
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while(n){
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n = n & (n-1)
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res++
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}
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return res
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};
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```
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##### [338. 比特位计数](https://leetcode-cn.com/problems/counting-bits/)
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给定一个非负整数 **num**。对于 **0 ≤ i ≤ num** 范围中的每个数字 **i** ，计算其二进制数中的 1 的数目并将它们作为数组返回。
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```js
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var countBits = function (num) {
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const res = []
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for (let i = 0; i <= num; i++) {
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let n = i
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let times = 0
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while (n) {
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n = n & (n - 1)
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times++
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}
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res.push(times)
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}
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return res
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};
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```
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##### [190. 颠倒二进制位](https://leetcode-cn.com/problems/reverse-bits/)
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颠倒给定的 32 位无符号整数的二进制位。
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```js
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var reverseBits = function (n) {
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let rev = 0;
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for (let i = 0; i < 32 && n > 0; ++i) {
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rev |= (n & 1) << (31 - i);
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n >>>= 1;
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}
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return rev >>> 0;
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};
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```
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##### [201. 数字范围按位与](https://leetcode-cn.com/problems/bitwise-and-of-numbers-range/)
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给你两个整数 `left` 和 `right` ，表示区间 `[left, right]` ，返回此区间内所有数字 **按位与** 的结果（包含 `left` 、`right` 端点）。
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```js
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var rangeBitwiseAnd = function (left, right) {
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let count = 0
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while (left !== right) {
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left >>= 1
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right >>= 1
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count++
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}
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return left << count
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};
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```
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## 总结
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玄
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## 练习
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- [single-number](https://leetcode-cn.com/problems/single-number/)
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- [single-number-ii](https://leetcode-cn.com/problems/single-number-ii/)
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- [single-number-iii](https://leetcode-cn.com/problems/single-number-iii/)
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- [number-of-1-bits](https://leetcode-cn.com/problems/number-of-1-bits/)
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- [counting-bits](https://leetcode-cn.com/problems/counting-bits/)
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- [reverse-bits](https://leetcode-cn.com/problems/reverse-bits/)

‎数据结构篇/栈和队列.md‎

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##### [94. 二叉树的中序遍历](https://leetcode-cn.com/problems/binary-tree-inorder-traversal/)
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```js
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var inorderTraversal = function (root) { //递归写法
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var inorderTraversal = function (root) { //递归
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if (root === null) {
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return []
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}
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```
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```js
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var inorderTraversal = function (root) {
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const stack = []
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const res = []
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let current = root
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while (stack.length > 0 || current) {
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while (current) {
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stack.push(current)
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current = current.left
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}
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current = stack.pop()
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res.push(current.val)
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current = current.right
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}
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return res
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};
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```
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##### [133.克隆图](https://leetcode-cn.com/problems/clone-graph/)
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给你无向 **[连通](https://baike.baidu.com/item/连通图/6460995?fr=aladdin)** 图中一个节点的引用，请你返回该图的 [**深拷贝**](https://baike.baidu.com/item/深拷贝/22785317?fr=aladdin)（克隆）。
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```js
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var cloneGraph = function (node) {
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let visited = new Map();
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return (function clone(node, visited) {
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if (!node) {
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return null
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}
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if (visited.has(node)) {
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return visited.get(node)
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}
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const newNode = new Node(node.val)
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visited.set(node, newNode)
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for (let i = 0; i < node.neighbors.length; i++) {
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newNode.neighbors[i] = clone(node.neighbors[i], visited)
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}
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return newNode
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})(node, visited)
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};
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```
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##### [200. 岛屿数量](https://leetcode-cn.com/problems/number-of-islands/)
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给你一个由 `'1'`（陆地）和 `'0'`（水）组成的的二维网格，请你计算网格中岛屿的数量。
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```js
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var numIslands = function (grid) {
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const nr = grid.length
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const nc = grid[0].length
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let resNum = 0
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for (let i = 0; i < nr; i++) {
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for (let j = 0; j < nc; j++) {
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if (grid[i][j] === '1') {
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resNum++
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dfs(grid, i, j)
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}
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}
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}
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return resNum
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};
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const dfs = (grid, row, col) => {
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const gr = grid.length
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const gc = grid[0].length
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if (row < 0 || col < 0 || row >= gr || col >= gc || grid[row][col] === '0') {
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return 0
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}
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grid[row][col] = '0'
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dfs(grid, row + 1, col)
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dfs(grid, row - 1, col)
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dfs(grid, row, col + 1)
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dfs(grid, row, col - 1)
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}
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```
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[84. 柱状图中最大的矩形](https://leetcode-cn.com/problems/largest-rectangle-in-histogram/)
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```js
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```
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### Queue 队列
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##### [232. 用栈实现队列](https://leetcode-cn.com/problems/implement-queue-using-stacks/)
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```js
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/**
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* Initialize your data structure here.
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*/
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var MyQueue = function () {
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this.stack1 = []
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this.stack2 = []
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};
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/**
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* Push element x to the back of queue.
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* @param {number} x
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* @return {void}
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*/
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MyQueue.prototype.push = function (x) {
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this.stack1.push(x)
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};
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/**
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* Removes the element from in front of queue and returns that element.
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* @return {number}
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*/
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MyQueue.prototype.pop = function () {
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if (this.stack2.length > 0) {
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return this.stack2.pop()
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} else {
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while (this.stack1.length > 0) {
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this.stack2.push(this.stack1.pop())
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}
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return this.stack2.pop()
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}
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};
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/**
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* Get the front element.
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* @return {number}
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*/
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MyQueue.prototype.peek = function () {
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if (this.stack2.length > 0) {
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return this.stack2[this.stack2.length - 1]
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} else {
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while (this.stack1.length > 0) {
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this.stack2.push(this.stack1.pop())
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}
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return this.stack2[this.stack2.length - 1]
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}
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};
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/**
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* Returns whether the queue is empty.
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* @return {boolean}
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*/
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MyQueue.prototype.empty = function () {
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if (this.stack1.length === 0 && this.stack2.length === 0) {
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return true
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}
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return false
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};
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```
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##### [542. 01 矩阵](https://leetcode-cn.com/problems/01-matrix/)
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```js
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var updateMatrix = function (matrix) {
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const dirs = [[-1, 0], [1, 0], [0, -1], [0, 1]]
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const m = matrix.length, n = matrix[0].length
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const dist = new Array(m).fill(new Array(n).fill(0))
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const seen = new Array(m).fill(new Array(n).fill(false))
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const queue = []
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for (let i = 0; i < m; i++) {
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for (let j = 0; j < n; j++) {
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if (matrix[i][j] === 0) {
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queue.push([i, j])
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seen[i][j] = true
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}
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}
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}
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while (queue.length > 0) {
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const [i, j] = queue.shift()
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for (let d = 0; d < 4; d++) {
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const ni = i + dirs[d][0]
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const nj = j + dirs[d][1]
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if (ni >= 0 && ni < m && nj >= 0 && nj < n && !seen[ni][nj]) {
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dist[ni][nj] = dist[i][j] + 1
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queue.push([ni, nj])
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seen[ni][nj] = true
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}
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}
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}
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return dist
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};
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```
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## 总结
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- 熟悉栈的使用场景
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- 后入先出，保存临时值
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- 利用栈 DFS 深度搜索
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- 熟悉队列的使用场景
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- 利用队列 BFS 广度搜索
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## 练习
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- [min-stack](https://leetcode-cn.com/problems/min-stack/)
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- [evaluate-reverse-polish-notation](https://leetcode-cn.com/problems/evaluate-reverse-polish-notation/)
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- [decode-string](https://leetcode-cn.com/problems/decode-string/)
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- [binary-tree-inorder-traversal](https://leetcode-cn.com/problems/binary-tree-inorder-traversal/)
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- [clone-graph](https://leetcode-cn.com/problems/clone-graph/)
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- [number-of-islands](https://leetcode-cn.com/problems/number-of-islands/)
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- [largest-rectangle-in-histogram](https://leetcode-cn.com/problems/largest-rectangle-in-histogram/)
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- [implement-queue-using-stacks](https://leetcode-cn.com/problems/implement-queue-using-stacks/)
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- [01-matrix](https://leetcode-cn.com/problems/01-matrix/)

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