From fbf52ee2bf0cad8c4231311ef2d87fc383a49a3c Mon Sep 17 00:00:00 2001 From: Luo <82520819+Jerry-306@users.noreply.github.com> Date: Fri, 11 Feb 2022 16:57:22 +0800 Subject: [PATCH] =?UTF-8?q?=E7=AE=97=E6=B3=95=E6=A8=A1=E6=9D=BF=E6=96=B0?= =?UTF-8?q?=E5=A2=9E=20typescript=20=E7=89=88=E6=9C=AC=E4=BB=A3=E7=A0=81?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/算法模板.md | 265 ++++++++++++++++++++++++++++++++++++++- 1 file changed, 264 insertions(+), 1 deletion(-) diff --git a/problems/算法模板.md b/problems/算法模板.md index a4136511..789d8f80 100644 --- a/problems/算法模板.md +++ b/problems/算法模板.md @@ -394,7 +394,7 @@ var postorder = function (root, list) { ```javascript var preorderTraversal = function (root) { let res = []; - if (root === null) return rs; + if (root === null) return res; let stack = [root], cur = null; while (stack.length) { @@ -536,6 +536,269 @@ function backtracking(参数) { } ``` +TypeScript： + +## 二分查找法 + +使用左闭右闭区间 + +```typescript +var search = function (nums: number[], target: number): number { + let left: number = 0, right: number = nums.length - 1; + // 使用左闭右闭区间 + while (left <= right) { + let mid: number = left + Math.floor((right - left)/2); + if (nums[mid] > target) { + right = mid - 1; // 去左面闭区间寻找 + } else if (nums[mid] < target) { + left = mid + 1; // 去右面闭区间寻找 + } else { + return mid; + } + } + return -1; +}; +``` + +使用左闭右开区间 + +```typescript +var search = function (nums: number[], target: number): number { + let left: number = 0, right: number = nums.length; + // 使用左闭右开区间 [left, right) + while (left < right) { + let mid: number = left + Math.floor((right - left)/2); + if (nums[mid] > target) { + right = mid; // 去左面闭区间寻找 + } else if (nums[mid] < target) { + left = mid + 1; // 去右面闭区间寻找 + } else { + return mid; + } + } + return -1; +}; +``` + +## KMP + +```typescript +var kmp = function (next: number[], s: number): void { + next[0] = -1; + let j: number = -1; + for(let i: number = 1; i < s.length; i++){ + while (j >= 0 && s[i] !== s[j + 1]) { + j = next[j]; + } + if (s[i] === s[j + 1]) { + j++; + } + next[i] = j; + } +} +``` + +## 二叉树 + +### 深度优先遍历（递归） + +二叉树节点定义： + +```typescript +class TreeNode { + val: number + left: TreeNode | null + right: TreeNode | null + constructor(val?: number, left?: TreeNode | null, right?: TreeNode | null) { + this.val = (val===undefined ? 0 : val) + this.left = (left===undefined ? null : left) + this.right = (right===undefined ? null : right) + } +} +``` + +前序遍历（中左右）： + +```typescript +var preorder = function (root: TreeNode | null, list: number[]): void { + if (root === null) return; + list.push(root.val); // 中 + preorder(root.left, list); // 左 + preorder(root.right, list); // 右 +} +``` + +中序遍历（左中右）： + +```typescript +var inorder = function (root: TreeNode | null, list: number[]): void { + if (root === null) return; + inorder(root.left, list); // 左 + list.push(root.val); // 中 + inorder(root.right, list); // 右 +} +``` + +后序遍历（左右中）： + +```typescript +var postorder = function (root: TreeNode | null, list: number[]): void { + if (root === null) return; + postorder(root.left, list); // 左 + postorder(root.right, list); // 右 + list.push(root.val); // 中 +} +``` + +### 深度优先遍历（迭代） + +前序遍历（中左右）： + +```typescript +var preorderTraversal = function (root: TreeNode | null): number[] { + let res: number[] = []; + if (root === null) return res; + let stack: TreeNode[] = [root], + cur: TreeNode | null = null; + while (stack.length) { + cur = stack.pop(); + res.push(cur.val); + cur.right && stack.push(cur.right); + cur.left && stack.push(cur.left); + } + return res; +}; +``` + +中序遍历（左中右）： + +```typescript +var inorderTraversal = function (root: TreeNode | null): number[] { + let res: number[] = []; + if (root === null) return res; + let stack: TreeNode[] = []; + let cur: TreeNode | null = root; + while (stack.length ！== 0 || cur !== null) { + if (cur !== null) { + stack.push(cur); + cur = cur.left; + } else { + cur = stack.pop(); + res.push(cur.val); + cur = cur.right; + } + } + return res; +}; +``` + +后序遍历（左右中）： + +```typescript +var postorderTraversal = function (root: TreeNode | null): number[] { + let res: number[] = []; + if (root === null) return res; + let stack: TreeNode[] = [root]; + let cur: TreeNode | null = null; + while (stack.length) { + cur = stack.pop(); + res.push(cur.val); + cur.left && stack.push(cur.left); + cur.right && stack.push(cur.right); + } + return res.reverse() +}; +``` + +### 广度优先遍历（队列） + +```typescript +var levelOrder = function (root: TreeNode | null): number[] { + let res: number[] = []; + if (root === null) return res; + let queue: TreeNode[] = [root]; + while (queue.length) { + let n: number = queue.length; + let temp: number[] = []; + for (let i: number = 0; i < n; i++) { + let node: TreeNode = queue.shift(); + temp.push(node.val); + node.left && queue.push(node.left); + node.right && queue.push(node.right); + } + res.push(temp); + } + return res; +}; +``` + +### 二叉树深度 + +```typescript +var getDepth = function (node: TreNode | null): number { + if (node === null) return 0; + return 1 + Math.max(getDepth(node.left), getDepth(node.right)); +} +``` + +### 二叉树节点数量 + +```typescript +var countNodes = function (root: TreeNode | null): number { + if (root === null) return 0; + return 1 + countNodes(root.left) + countNodes(root.right); +} +``` + +## 回溯算法 + +```typescript +function backtracking(参数) { + if (终止条件) { + 存放结果; + return; + } + + for (选择：本层集合中元素（树中节点孩子的数量就是集合的大小）) { + 处理节点; + backtracking(路径，选择列表); // 递归 + 回溯，撤销处理结果 + } +} + +``` + +## 并查集 + +```typescript + let n: number = 1005; // 根据题意而定 + let father: number[] = new Array(n).fill(0); + + // 并查集初始化 + function init () { + for (int i: number = 0; i < n; ++i) { + father[i] = i; + } + } + // 并查集里寻根的过程 + function find (u: number): number { + return u === father[u] ? u : father[u] = find(father[u]); + } + // 将v->u 这条边加入并查集 + function join(u: number, v: number) { + u = find(u); + v = find(v); + if (u === v) return ; + father[v] = u; + } + // 判断 u 和 v是否找到同一个根 + function same(u: number, v: number): boolean { + u = find(u); + v = find(v); + return u === v; + } +``` + Java：