chore: improve Ternary Search algorithm

Author: hasanalkaf3

Search/TernarySearch.js

@@ -12,38 +12,33 @@
  */
 
 function ternarySearchRecursive(arr, key, low = 0, high = arr.length - 1) {
-  if (high >= low) {
-    // find the mid1 and mid2
-    const mid1 = Math.floor(low + (high - low) / 3)
-    const mid2 = Math.floor(high - (high - low) / 3)
+  // if low > high => we have searched the whole array without finding the item
+  if (low > high) return -1
 
-    // check if key is found at any mid
-    if (arr[mid1] === key) {
-      // return index of key if found
-      return mid1
-    }
-    if (arr[mid2] === key) {
-      // return index of key if found
-      return mid2
-    }
+  // find the mid1 and mid2
+  const mid1 = Math.floor(low + (high - low) / 3)
+  const mid2 = Math.floor(high - (high - low) / 3)
 
-    // since the key is not found at mid,
-    // check in which region it is present
-    // and repeat the Search operation
-    // in that region
-    if (key < arr[mid1]) {
-      // the key lies in between low and mid1
-      return ternarySearchRecursive(arr, key, low, mid1 - 1)
-    } else if (key > arr[mid2]) {
-      // the key lies in between mid2 and high
-      return ternarySearchRecursive(arr, key, mid2 + 1, high)
-    } else {
-      // the key lies in between mid1 and mid2
-      return ternarySearchRecursive(arr, key, mid1 + 1, mid2 - 1)
-    }
+  // check if key is found at any mid
+  // return index of key if found
+  if (arr[mid1] === key) return mid1
+
+  // return index of key if found
+  if (arr[mid2] === key) return mid2
+
+  // since the key is not found at mid,
+  // check in which region it is present
+  // and repeat the Search operation
+  // in that region
+  if (key < arr[mid1]) {
+    // the key lies in between low and mid1
+    return ternarySearchRecursive(arr, key, low, mid1 - 1)
+  } else if (key > arr[mid2]) {
+    // the key lies in between mid2 and high
+    return ternarySearchRecursive(arr, key, mid2 + 1, high)
   } else {
-    // if low > high => we have searched the whole array without finding the item
-    return -1
+    // the key lies in between mid1 and mid2
+    return ternarySearchRecursive(arr, key, mid1 + 1, mid2 - 1)
   }
 }
 
@@ -54,14 +49,11 @@ function ternarySearchIterative(arr, key, low = 0, high = arr.length - 1) {
     const mid2 = Math.floor(high - (high - low) / 3)
 
     // check if key is found at any mid
-    if (arr[mid1] === key) {
-      // return index of key if found
-      return mid1
-    }
-    if (arr[mid2] === key) {
-      // return index of key if found
-      return mid2
-    }
+    // return index of key if found
+    if (arr[mid1] === key) return mid1
+
+    // return index of key if found
+    if (arr[mid2] === key) return mid2
 
     // since the key is not found at mid,
     // check in which region it is present
@@ -75,8 +67,7 @@ function ternarySearchIterative(arr, key, low = 0, high = arr.length - 1) {
       low = mid2 + 1
     } else {
       // the key lies in between mid1 and mid2
-      low = mid1 + 1
-      high = mid2 - 1
+      ;[low, high] = [mid1 + 1, mid2 - 1]
     }
   }
   // the key was not found

Search/test/TernarySearch.test.js

@@ -29,13 +29,13 @@ test('should return the index of a number in an array of numbers:', () => {
 test('should return the index of a string in an array of strings:', () => {
   const indexNumber = ternarySearchRecursive(
     ['Ali', 'Cathrynli', 'Josuke', 'Thomas'],
-    'Cathrynli'
+    'Josuke'
   )
-  expect(indexNumber).toBe(1)
+  expect(indexNumber).toBe(2)
 })
 
 test('should return the index of a string in an array of strings:', () => {
-  const indexNumber = ternarySearchRecursive(
+  const indexNumber = ternarySearchIterative(
     ['Ali', 'Cathrynli', 'Josuke', 'Thomas'],
     'Josuke'
   )
@@ -49,3 +49,11 @@ test('should return the index of a string in an array of strings:', () => {
   )
   expect(indexNumber).toBe(-1)
 })
+
+test('should return the index of a string in an array of strings:', () => {
+  const indexNumber = ternarySearchIterative(
+    ['Ali', 'Cathrynli', 'Josuke', 'Thomas'],
+    'Angela'
+  )
+  expect(indexNumber).toBe(-1)
+})