添加笔试题

Author: code.wang

.vscode/launch.json

@@ -4,6 +4,116 @@
 
 // import './string/main'
 
-import './动态规划/main'
+// import './动态规划/main'
 
-// import './数组/main'
+// import './数组/main'
+
+// import './查找/main'
+
+(function(target){
+    console.log(target)
+    const result = [];
+    let start = 1;
+    let end = 2;
+    let sum = start + end;
+    while (start != end && end <= target) {
+        if(sum === target){
+            result.push( getSubSequence(start, end) )
+            ++b;
+            sum += b;
+        } else if(sum > target){
+            sum -= start;
+            ++start
+        } else {
+            ++end;
+            // sum += 
+        }
+    }
+    return result;
+})
+
+function getSubSequence(start, end){
+    const res = [];
+    for (let i = start; i < end; i++){
+        res.push(i)
+    }
+    return res;
+}
+
+//动态规划最大和子序列
+var maxSubArray = function(nums) {
+    // let ans = nums[0];
+    // let sum = 0;
+    // for (let i = 1; i < nums.length; i++) {
+    //     if(sum > 0){
+    //         sum += nums[i];
+    //     } else {
+    //         sum = nums[i];
+    //     }
+    //     ans = Math.max(ans, sum);
+    // }
+    // return ans
+    const dp = [];
+    dp[0] = nums[0];
+    let max = nums[0];
+    for (let i = 1; i< nums.length; i++) {
+        dp[i] = Math.max(dp[i-1] + nums[i], nums[i]);
+        max = Math.max(max, dp[i]);
+    }
+    return max;
+};
+
+// console.log( maxSubArray([-2,1,-3,4,-1,2,1,-5,4]) )
+function isFlag (str) {
+    const n = str.length - 1;
+    for (let i = 0; i < n / 2; i++) {
+        if(str[i] !== str[n - i]){
+            return false;
+        }
+    }
+    return true
+}
+
+function longestPalindrome(str){
+    let res = '';
+    for (let i = 0; i < str.length; i ++){
+        for (let j = i + 1; j < str.length + 1; j++){
+            const s = str.substring(i, j);
+            if(s.length < res.length) continue;
+            if(isFlag(s) ){
+                res = s;
+            }
+        }
+    }
+    return res
+}
+
+// console.log( longestPalindrome("aacabdkacaa"))
+const dp = [];
+
+/**
+ * @param {number} n
+ * @return {number}
+ */
+var fib = function(n) {
+    if(n === 0) return 0;
+    if( n === 1 ) return 1;
+    if(fib.dp[n]) return fib.dp[n];
+    fib.dp[n] = fib(n - 1) + fib(n - 2);
+    return fib.dp[n];
+};
+fib.dp = [];
+
+var tribonacci = function(n) {
+    if(n === 0) return 0;
+    if( n === 1 ) return 1;
+    if( n === 2 ) return 1;
+    if(tribonacci.dp[n]) return tribonacci.dp[n];
+    tribonacci.dp[n] = tribonacci(n - 1) + tribonacci(n - 2) + tribonacci(n - 3);
+    return tribonacci.dp[n];
+};
+tribonacci.dp = [];
+
+console.time()
+console.log( tribonacci(4) )
+console.timeEnd()

main.js

@@ -0,0 +1,2 @@
+null 没有对象也没有对象的引用
+undefined 有对象的引用，但是指向的对象不存在

rk.md

@@ -0,0 +1,27 @@
+/**
+ * @param {number[]} nums
+ * @param {number} target
+ * @return {number}
+ */
+const search = (nums, target) => {
+    let left = 0;
+    let right = nums.length - 1;
+    while(left <= right) {
+        const mid = Math.floor((right + left) / 2);
+        const midValue = nums[mid];
+        if(midValue > target){
+            right = mid - 1;
+        } else if ( midValue < target){
+            left = mid + 1;
+        } else {
+            return mid;
+        }
+    }
+    return -1;
+};
+
+// console.log(search([-1], -1));
+// 输入一个正整数target，输出所有和为target的连续正整数的序列，
+const test = () => {
+
+}

查找/main.js

@@ -0,0 +1,39 @@
+console.log({}+[]); // [Object Object] 会调用toString方法
+{}+[];//[object Object]
+[]+{};   //[object Object]
+{} + {};  // "[object Object][object Object]"
+console.log([] == false)  // true
+console.log({} == false)  // false
+if([]){
+    console.log([] == false) 
+}
+// ???? 为什么在if语句中[]为true
+("b" + "a" + + "a" + "a").toLocaleLowerCase(); 
+0 == "0"
+Boolean("0") == Boolean(0) // true
+console.log(NaN == 0); // false
+console.log(NaN <= 0); // 
+console.log(null <= 0); 
+console.log(1 + null); 
+var a ={value:1};
+var b ={value:2}; 
+console.log(a<=b);
+var obj={};
+var x = +obj.yideng?.name ?? 'test'; 
+console.log(x);
+var test="test"; 
+console.log(typeof test);  // true
+console.log(test instanceof String); // true ???
+
+Promise.resolve().then(() => {
+    console.log(11); 
+})
+    .then(() => { 
+        console.log(12);
+    })
+    .then(() => {
+        console.log(0);
+        return Promise.resolve(5); })
+    .then((r) => { 
+        console.log('🐻 ', r);
+    });

笔试题/js基础/ces.js

@@ -2,6 +2,7 @@ import { bianli } from "../utils/linkList";
 import { deleteNode } from "./deleteLinkLIstItem";
 import { ListNode } from "./myLinkList";
 import { getIntersectionNode } from './leetcode160相交链表'
+import { removeElements } from "./移除链表元素";
 
 const a = new ListNode(4)
 const b = new ListNode(5)
@@ -33,4 +34,10 @@ export const mapArruyToLinklist = (arr) => {
 
 const listA = [4,1,8,4,5], listB = [5,0,1,8,4,5];
 
-console.log( getIntersectionNode( mapArruyToLinklist(listA), mapArruyToLinklist(listB) ))
+const listTest = mapArruyToLinklist([1, 7,7,7, 7])
+
+const newList = removeElements(listTest, 7)
+// console.log(newList)
+bianli(newList)
+
+// console.log( getIntersectionNode( mapArruyToLinklist(listA), mapArruyToLinklist(listB) ))

链表/main.js

@@ -0,0 +1,33 @@
+// 给你一个链表的头节点 head 和一个整数 val ，请你删除链表中所有满足 Node.val == val 的节点，并返回 新的头节点 。
+// 输入：head = [1,2,6,3,4,5,6], val = 6
+// 输出：[1,2,3,4,5]
+
+import { bianli } from "../utils/linkList";
+import { ListNode } from "./myLinkList";
+
+/**
+ * @param {ListNode} head
+ * @param {number} val
+ * @return {ListNode}
+ */
+// export var removeElements = function(head, val) {
+//     if(head === null) return head;
+//     head.next = removeElements(head.next, val);
+//     return head.val === val ? head.next : head;
+// };
+
+export var removeElements = function(head, val) {
+    //创建一个虚拟头结点
+    let dummyNode = new ListNode(val-1);
+    dummyNode.next=head;
+    let prev=dummyNode;
+    //确保当前结点后还有结点
+    while(prev.next!=null){
+        if(prev.next.val==val){
+            prev.next=prev.next.next;
+        }else{
+            prev=prev.next;
+        }
+    }
+    return dummyNode.next;
+};