samflab

 int findMissing(int arr[], int n) { 
        for(int i = 0; i < n; i++){
          //looking for all the conditions
            while(arr[i] >= 1 && arr[i] <= n && arr[i] != arr[arr[i]-1])
                swap(arr[i], arr[arr[i]-1]);
        }
   //to check our missing number. For explaination, refer the article.
        for(int i = 0; i < n; i++){
            if(arr[i] != i + 1)
                return i + 1;

samflab

import "./App.css";

function App() {
  return (
    <div className="App">
     
    </div>
  );
}

samflab

import "./App.css";

function App() {
  return (
    <div className="App">
      <h1 className="heading">Cash Register Manager</h1>
      <div className="cash-register">
        <div className="form">
        </div>

samflab

<div className="form">
    <label>Bill</label>
    <input type="number" placeholder="0"></input>
    <br />
    <label>Cash Given</label>
    <input type="number" placeholder="0"></input>
    <br />
    <button>Return Change</button>
</div>

samflab

.App {
  display: flex;
  flex-direction: column;
  align-items: center;
  font-family: monospace;
}
.heading {
  padding-top: 20vh;
  font-size: xx-large;
}