diff --git a/Search/ExponentialSearch.js b/Search/ExponentialSearch.js new file mode 100644 index 000000000..d866ed5d8 --- /dev/null +++ b/Search/ExponentialSearch.js @@ -0,0 +1,61 @@ +/* + * Exponential Search + * + * The algorithm consists of two stages. The first stage determines a + * range in which the search key would reside if it were in the list. + * In the second stage, a binary search is performed on this range. + * + * + * + */ + +function binarySearch(arr, x, floor, ceiling) { + // Middle index + let mid = Math.floor((floor + ceiling) / 2); + + // If value is at the mid position return this position + if (arr[mid] === x) { + return mid; + } + + if(floor > ceiling) return -1; + + // If the middle element is great than the value + // search the left part of the array + if (arr[mid] > value) { + return binarySearch(arr, value, floor, mid - 1); + //If the middle element is lower than the value + //search the right part of the array + } else { + return binarySearch(arr, value, mid + 1, ceiling); + } + + +} + + +function exponentialSearch(arr, length, value) { + // If value is the first element of the array return this position + if (arr[0] == value) { + return 0; + } + + // Find range for binary search + let i = 1; + while (i < length && arr[i] <= value) { + i = i * 2; + } + + // Call binary search for the range found above + return binarySearch(arr, value, i / 2, Math.min(i, length)); +} + +let arr = [2, 3, 4, 10, 40, 65 , 78 , 100]; +let value = 78; +let result = exponentialSearch(arr, arr.length, value); + +if (result < 0) { + console.log("Element not found"); +} else { + console.log("Element found at position :" + result); +} diff --git a/Search/InterpolationSearch.js b/Search/InterpolationSearch.js new file mode 100644 index 000000000..f9a54bf60 --- /dev/null +++ b/Search/InterpolationSearch.js @@ -0,0 +1,49 @@ +/* + * Interpolation Search + * + * Time Complexity: + * -Best case: O(1) + * -Worst case: O(n) + * -O((log(log(n))) If the data are uniformly distributed + * + * + */ + +function interpolationSearch(arr, key) { + + let length = arr.length - 1; + let low = 0; + let high = length; + let position = -1; + let delta = -1; + + //Because the array is sorted the key must be between low and high + while (low <= high && key >= arr[low] && key <= arr[high]) { + + delta = (key - arr[low]) / (arr[high] - arr[low]); + position = low + Math.floor((high - low) * delta); + + //Target found return its position + if (arr[position] === key) { + return position; + } + + //If the key is larger then it is in the upper part of the array + if (arr[position] < key) { + low = position + 1; + //If the key is smaller then it is in the lower part of the array + } else { + high = position - 1; + } + } + + return -1; +} + + +let arr = [2, 6, 8, 10, 12, 14, 16, 18, 20, 22, 26, 34, 39]; + +console.log("Found at position :" + interpolationSearch(arr, 2)); +console.log("Found at position :" + interpolationSearch(arr, 12)); +console.log("Found at position :" + interpolationSearch(arr, 1000)); +console.log("Found at position :" + interpolationSearch(arr, 39)); \ No newline at end of file