|
5 | 5 | */ |
6 | 6 |
|
7 | 7 | class FenwickTree { |
8 | | - constructor(feneickArray, array, n) { |
9 | | - for (let i = 1; i <= n; i++) { |
10 | | - feneickArray[i] = 0 |
11 | | - } |
12 | | - for (let i = 0; i < n; i++) { |
13 | | - this.update(feneickArray, n, i, array[i]) |
14 | | - } |
15 | | - } |
| 8 | + /** |
| 9 | + * Constructs a Fenwick Tree. |
| 10 | + * @param {Array} fenwickArray The Fenwick Tree array to be initialized. |
| 11 | + * @param {Array} array The input array whose prefix sum is to be calculated. |
| 12 | + * @param {number} n The size of the input array. |
| 13 | + */ |
| 14 | + constructor(feneickArray, array, n) { |
| 15 | + for (let i = 1; i <= n; i++) { |
| 16 | + feneickArray[i] = 0 |
| 17 | + } |
| 18 | + for (let i = 0; i < n; i++) { |
| 19 | + this.update(feneickArray, n, i, array[i]) |
| 20 | + } |
| 21 | + } |
16 | 22 |
|
17 | | - update(feneickArray, n, index, value) { |
18 | | - index = index + 1 |
19 | | - while (index <= n) { |
20 | | - feneickArray[index] += value |
21 | | - index += index & -index |
22 | | - } |
23 | | - } |
| 23 | + /** |
| 24 | + * Updates the Fenwick Tree with a new value at the specified index. |
| 25 | + * @param {Array} fenwickArray The Fenwick Tree array. |
| 26 | + * @param {number} n The size of the Fenwick Tree array. |
| 27 | + * @param {number} index The index at which the value is updated. |
| 28 | + * @param {number} value The new value to be added at the index. |
| 29 | + */ |
| 30 | + update(feneickArray, n, index, value) { |
| 31 | + index = index + 1 |
| 32 | + while (index <= n) { |
| 33 | + feneickArray[index] += value |
| 34 | + index += index & -index |
| 35 | + } |
| 36 | + } |
24 | 37 |
|
25 | | - getPrefixSum(feneickArray, index) { |
26 | | - let currSum = 0 |
27 | | - index = index + 1 |
28 | | - while (index > 0) { |
29 | | - currSum += feneickArray[index] |
30 | | - index -= index & -index |
31 | | - } |
| 38 | + getPrefixSum(feneickArray, index) { |
| 39 | + let currSum = 0 |
| 40 | + index = index + 1 |
| 41 | + while (index > 0) { |
| 42 | + currSum += feneickArray[index] |
| 43 | + index -= index & -index |
| 44 | + } |
32 | 45 |
|
33 | | - return currSum |
34 | | - } |
| 46 | + return currSum |
| 47 | + } |
35 | 48 | } |
36 | 49 | export { FenwickTree } |
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