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1 | 1 | /** |
2 | 2 | * Note: Array must be sorted for ternary search |
3 | | - * Complexity: |
| 3 | + * Complexity: |
4 | 4 | * Worst case time complexity: O(log N) |
5 | 5 | * Average case time complexity: O(log N) |
6 | 6 | * Best case time complexity: O(1) |
7 | 7 | * Space complexity: O(1) |
8 | 8 | */ |
9 | | -function ternarySearch(arr, key){ |
10 | | - let low = 0; |
11 | | - let high = arr.length - 1; |
12 | | - while(low <= high){ |
13 | | - let lowMiddle = low + Math.floor((high - low) / 3); |
14 | | - let highMiddle = low + 2 * Math.floor((high - low) / 3); |
15 | | - if(key == arr[low]){ |
16 | | - return low; |
17 | | - } else if(key == arr[high]){ |
18 | | - return high; |
19 | | - } else if(key <= arr[lowMiddle]){ |
20 | | - high = lowMiddle; |
21 | | - } else if(key > arr[lowMiddle] && key <= arr[highMiddle]){ |
22 | | - low = lowMiddle + 1; |
23 | | - high = highMiddle; |
24 | | - } else { |
25 | | - low = highMiddle + 1; |
26 | | - } |
| 9 | +function ternarySearch(arr, key) { |
| 10 | + let low = 0; |
| 11 | + let high = arr.length - 1; |
| 12 | + while (low <= high) { |
| 13 | + const lowMiddle = low + Math.floor((high - low) / 3); |
| 14 | + const highMiddle = low + 2 * Math.floor((high - low) / 3); |
| 15 | + if (key === arr[low]) { |
| 16 | + return low; |
| 17 | + } if (key === arr[high]) { |
| 18 | + return high; |
| 19 | + } if (key <= arr[lowMiddle]) { |
| 20 | + high = lowMiddle; |
| 21 | + } else if (key > arr[lowMiddle] && key <= arr[highMiddle]) { |
| 22 | + low = lowMiddle + 1; |
| 23 | + high = highMiddle; |
| 24 | + } else { |
| 25 | + low = highMiddle + 1; |
27 | 26 | } |
28 | | - return null; |
| 27 | + } |
| 28 | + return null; |
29 | 29 | } |
30 | 30 |
|
31 | | -function ternarySearchRecursive(arr, low, high, key){ |
32 | | - if(high >= low){ |
33 | | - let highMiddle = low + 2 * Math.floor((high - low) / 3); |
34 | | - let lowMiddle = low + Math.floor((high - low) / 3); |
35 | | - if(key === arr[lowMiddle]){ |
36 | | - return lowMiddle; |
37 | | - } else if(key === arr[highMiddle]){ |
38 | | - return highMiddle; |
39 | | - } else if(key < arr[lowMiddle]){ |
40 | | - return ternarySearchRecursive(arr, low, lowMiddle - 1, key); |
41 | | - } else if(key > arr[lowMiddle] && key < arr[highMiddle]){ |
42 | | - return ternarySearchRecursive(arr, lowMiddle + 1, highMiddle - 1, key); |
43 | | - } else { |
44 | | - return ternarySearchRecursive(arr, highMiddle + 1, high, key); |
45 | | - } |
46 | | - } |
47 | | - return null; |
| 31 | +function ternarySearchRecursive(arr, low, high, key) { |
| 32 | + if (high >= low) { |
| 33 | + const highMiddle = low + 2 * Math.floor((high - low) / 3); |
| 34 | + const lowMiddle = low + Math.floor((high - low) / 3); |
| 35 | + if (key === arr[lowMiddle]) { |
| 36 | + return lowMiddle; |
| 37 | + } if (key === arr[highMiddle]) { |
| 38 | + return highMiddle; |
| 39 | + } if (key < arr[lowMiddle]) { |
| 40 | + return ternarySearchRecursive(arr, low, lowMiddle - 1, key); |
| 41 | + } if (key > arr[lowMiddle] && key < arr[highMiddle]) { |
| 42 | + return ternarySearchRecursive(arr, lowMiddle + 1, highMiddle - 1, key); |
| 43 | + } |
| 44 | + return ternarySearchRecursive(arr, highMiddle + 1, high, key); |
| 45 | + } |
| 46 | + return null; |
48 | 47 | } |
49 | 48 |
|
50 | 49 | module.exports = { |
51 | | - ternarySearch, |
52 | | - ternarySearchRecursive |
| 50 | + ternarySearch, |
| 51 | + ternarySearchRecursive, |
53 | 52 | }; |
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