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| 1 | +'use strict'; |
| 2 | +function minHeapify(arr, rootIndex, n) { |
| 3 | + let smallestIndex = rootIndex; |
| 4 | + let leftIndex = (rootIndex * 2) + 1; |
| 5 | + let rightIndex = (rootIndex * 2) + 2; |
| 6 | + if (leftIndex < n && arr[smallestIndex] > arr[leftIndex]) smallestIndex = leftIndex; |
| 7 | + if (rightIndex < n && arr[smallestIndex] > arr[rightIndex]) smallestIndex = rightIndex; |
| 8 | + if (smallestIndex != rootIndex) { |
| 9 | + let temp = arr[rootIndex]; |
| 10 | + arr[rootIndex] = arr[smallestIndex]; |
| 11 | + arr[smallestIndex] = temp; |
| 12 | + minHeapify(arr, smallestIndex, n); |
| 13 | + } |
| 14 | +} |
| 15 | + |
| 16 | +function findSumBetweenK1nK2(arr, k1, k2) { |
| 17 | + // construct min heap |
| 18 | + for (let index = (arr.length / 2) - 1; index >= 0; index--) |
| 19 | + minHeapify(arr, index, arr.length) |
| 20 | + |
| 21 | + for (let index = 0; index < k1; index++) { |
| 22 | + minHeapify(arr, 0, arr.length - index); |
| 23 | + let temp = arr[0]; |
| 24 | + arr[0] = arr[arr.length - 1 - index]; |
| 25 | + arr[arr.length - 1 - index] = temp; |
| 26 | + } |
| 27 | + let sum = 0; |
| 28 | + for (let index = k1; index < (k2 - 1); index++) { |
| 29 | + minHeapify(arr, 0, arr.length - index); |
| 30 | + sum = sum + arr[0]; |
| 31 | + let temp = arr[0]; |
| 32 | + arr[0] = arr[arr.length - 1 - index]; |
| 33 | + arr[arr.length - 1 - index] = temp; |
| 34 | + } |
| 35 | + return sum; |
| 36 | +} |
| 37 | +// Sum of elements between k1th and k2th smallest elements |
| 38 | +let array = [20, 8, 22, 4, 12, 10, 14]; |
| 39 | +let k1 = 3, k2 = 6; |
| 40 | +// k1th smallest element is 10, k2th smallest element is 20 |
| 41 | +// and sum between these two elements are [12, 14] = 26 |
| 42 | +console.log('sum between ' + k1 + ' and ' + k2 + ' smallest elements is = ' + findSumBetweenK1nK2(array, k1, k2)) |
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