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JavaScript program to find the k largest elements of an array in original order

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2023-09-01 11:17:061456browse

JavaScript 程序按原始顺序查找数组的 k 个最大元素

We will use JavaScript array sorting methods and slicing techniques to find the k largest elements of the array in original order. First, we sort the array in descending order and then slice from the beginning to the kth index to get the largest k elements. By preserving the original order of elements, the significance and context of the data remains intact, making it easier for us to analyze and interpret the results.

method

The method of finding the k largest elements in an array in original order can be described as follows -

  • Create a new empty array to store up to k elements.

  • Loop through the input array and compare each element to an element in the new array.

  • If the new array has less than k elements, just add the current element to the new array.

  • If the new array has k elements, compare the current element with the smallest element in the new array.

  • If the current element is larger than the smallest element, delete the smallest element and add the current element to the new array.

  • Finally, return a new array containing up to k elements in the original order they appeared in the input array.

Example

This is a complete working JavaScript example for finding the k largest elements of an array in original order -

function findKMaxElements(arr, k) {
   
   // Create a copy of the original array
   let sortedArr = [...arr];
   
   // Sort the copy of the array in descending order
   sortedArr.sort((a, b) => b - a);
   
   // Slice the first k elements of the sorted array
   let kMaxElements = sortedArr.slice(0, k);
   
   // Create a result array to store the k maximum elements in their original order
   let result = [];
   
   // Loop through the original array
   for (let i = 0; i < arr.length; i++) {
      
      // Check if the current element is in the kMaxElements array
      if (kMaxElements.includes(arr[i])) {
         
         // If yes, add it to the result array
         result.push(arr[i]);
         
         // Remove the element from the kMaxElements array
         
         // to keep track of the elements that have already been added to the result
         kMaxElements.splice(kMaxElements.indexOf(arr[i]), 1);
         
         // If the kMaxElements array is empty, it means all k maximum elements have been found
         if (kMaxElements.length === 0) {
            break;
         }
      }
   }
   
   // Return the result array
   return result;
}
// Test the function with an example array
let arr = [3, 2, 1, 4, 5];
let k = 3;
console.log(findKMaxElements(arr, k));

illustrate

  • Function findKMaxElements takes an array arr and an integer k as input.

  • The first step is to create a copy of the original array arr and sort it in descending order using the sort method. This will allow us to easily find the k largest elements.

  • The
  • slice method is used to extract the first k elements of the sorted array and store them in a new array kMaxElements.

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  • Create the result array to store the k largest elements in original order.

  • The for loop is used to loop through the original array arr. For each element in the array, the code checks if it is in the kMaxElements array using the includes method.

  • If the current element is in the kMaxElements array, add it to the result array. The splice method is used to remove elements from the kMaxElements array to keep track of elements that have been added to the result.

  • The loop continues until all k largest elements are found and added to the resulting array, or the end of the original array is reached.

  • The final step is to return the resultarray containing the maximum k elements in the original array in original order.

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