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React usePrevious Hook

Oct 15, 2022CodeCatch
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LeetCode - Remove Element

Oct 22, 2024C S

0 likes • 2 views

function removeElement(nums: number[], val: number): number {
let zeroStartIndex = 0;
for(let i = 0; i < nums.length; i++) {
if(nums[i] !== val) {
nums[zeroStartIndex] = nums[i];
zeroStartIndex++;
}
}
return zeroStartIndex;
};

Depth-First Search in TypeScript

Oct 15, 2022CodeCatch

0 likes • 60 views

class DFS
{
public dfs(G: DFSGraph, startVert: number)
{
let visited: boolean[] = Array<boolean>();
// Pre-populate array:
for(let i = 0; i < G.size; i++)
{
visited.push(false);
}
let s: number[] = new Array();
visited[startVert] = true;
s.push(startVert);
while(s.length > 0)
{
const v = s.pop();
for(let adjV of G.adj[v])
{
if(!visited[adjV])
{
visited[adjV] = true;
s.push(adjV);
}
}
}
}
public dfsRecursive(G: DFSGraph, startVert: number)
{
let visited: boolean[] = Array<boolean>();
// Pre-populate array:
for(let i = 0; i < G.size; i++)
{
visited.push(false);
}
this.dfsAux(G, startVert, visited);
}
private dfsAux(G: DFSGraph, v: number, visited: boolean[])
{
visited[v] = true;
for(let adjV of G.adj[v])
{
if(!visited[adjV])
{
// this.foo(); // Something can happen before the visit.
this.dfsAux(G, adjV, visited);
// this.bar(); // Something can happen after the visit.
}
}
}
}

LeetCode - Two Sum

Oct 22, 2024C S

0 likes • 1 view

function twoSum(nums: number[], target: number): number[] {
const map = new Map();
for(let i = 0; i < nums.length; i++) {
if(map.has(target - nums[i])) {
return [map.get(target - nums[i]), i];
} else {
map.set(nums[i], i);
}
}
return []
}

retryPromise.ts

Oct 20, 2023LeifMessinger

0 likes • 7 views

//Retries maxRetries number of times, meaning that if you have 0, then it'll run the function once.
async function retryPromise<T>(
promiseFn: () => Promise<T>,
maxRetries = 3,
delayOffset = 0,
delayRandomRange = 0
): Promise<T> {
return new Promise<T>((resolve, reject) => {
promiseFn()
.then(resolve, (error: any) => { //On error
if (maxRetries <= 0) {
return reject(error);
} else {
if(delayRandomRange * Math.random() + delayOffset < 1.0){
return retryPromise(promiseFn, maxRetries - 1, delayOffset, delayRandomRange).then(resolve, reject);
}else{
return new Promise<T>((resolveTwo, rejectTwo) => {
setTimeout(() => {
return retryPromise(promiseFn, maxRetries - 1, delayOffset, delayRandomRange).then(resolveTwo, rejectTwo);
}, delayRandomRange * Math.random() + delayOffset);
}).then(resolve, reject);
}
}
});
});
}
//Returns a function that will fail numTimes times, then will return aValue
function functionThatReturnsAFunctionThatFailsACoupleTimes(numTimes: number, aValue: any): () => Promise<any> {
return async function(){
if(numTimes == 0){
return aValue;
}
numTimes--;
throw false;
};
}
const SMALL_NUMBER = 10;
function testTest(failNumberOfTimes: number){
let functionThatFailsACoupleTimes = functionThatReturnsAFunctionThatFailsACoupleTimes(failNumberOfTimes, true);
//Test my test
for(let i = 0; i < (failNumberOfTimes * 2); ++i){
function evalTest(val: any){
let testTestFailedReason = "";
if(val === undefined){
testTestFailedReason = "Test test returned undefined for some reason.";
}
if((i + 1) > failNumberOfTimes){
if(val === true){
//We're good
}else{
testTestFailedReason = "Test test didn't return true when it should have.";
}
}else{
if(val === false){
//We're good
}else{
testTestFailedReason = "Test test didn't return false when it should have.";
}
}
testTestFailedReason = testTestFailedReason || "Test test passed test case";
console.log(testTestFailedReason, "at index", i, "where the function returned", val);
}
functionThatFailsACoupleTimes().then(evalTest, evalTest)
};
}
testTest(SMALL_NUMBER);
let testCaseCounter = 1;
const throwsNoError = [
(val: any) => {
if(val == true){
console.log("Passed test case " + testCaseCounter++);
}else{
console.error("Unexpected return value", val);
}
},
() => {
console.error("It wasn't supposed to fail!")
}
]
const throwsError = [
(val: any) => {
console.error("It wasn't supposed to succeed!", val);
},
(val: any) => {
if(val == false){
console.log("Passed test case " + testCaseCounter++);
}else{
console.error("Unexpected return value", val);
}
}
];
//Runs SMALL_NUMBER times, because SMALL_NUMBER - 1 is the number of retries after the first one
let functionThatFailsACoupleTimes = functionThatReturnsAFunctionThatFailsACoupleTimes(SMALL_NUMBER - 1, true);
retryPromise(functionThatFailsACoupleTimes, SMALL_NUMBER - 1).then(...throwsNoError)
functionThatFailsACoupleTimes = functionThatReturnsAFunctionThatFailsACoupleTimes(SMALL_NUMBER - 1, true);
//Runs SMALL_NUMBER - 1 times, because SMALL_NUMBER - 2 is the number of retries after the first one
retryPromise(functionThatFailsACoupleTimes, SMALL_NUMBER - 2).then(...throwsError)
//Testing the delay. You'll have to wait a bit too.
functionThatFailsACoupleTimes = functionThatReturnsAFunctionThatFailsACoupleTimes(SMALL_NUMBER - 1, true);
//Runs SMALL_NUMBER times, because SMALL_NUMBER - 1 is the number of retries after the first one
retryPromise(functionThatFailsACoupleTimes, SMALL_NUMBER - 1, 500, 500).then(...throwsNoError)
functionThatFailsACoupleTimes = functionThatReturnsAFunctionThatFailsACoupleTimes(SMALL_NUMBER - 1, true);
//Runs SMALL_NUMBER - 1 times, because SMALL_NUMBER - 2 is the number of retries after the first one
retryPromise(functionThatFailsACoupleTimes, SMALL_NUMBER - 2, 500, 500).then(...throwsError)

typescript hello

Nov 21, 2023AustinLeath

0 likes • 25 views

// Print Hello, World!
console.log("Hello, World!");

LeetCode - Search Insert Position

Oct 22, 2024C S

0 likes • 2 views

function binarySearch(nums: number[], target: number): number {
let left = 0;
let right = nums.length - 1;
while (left <= right) {
const mid = left + Math.floor((right - left) / 2);
if (nums[mid] === target) {
return mid;
} else if (nums[mid] < target) {
left = mid + 1;
} else {
right = mid - 1;
}
}
return left;
}
function searchInsert(nums: number[], target: number): number {
return binarySearch(nums, target);
};