Merge pull request #113 from gabrielastelescu/binary-search-iterative

fix(runtimes/02-binary-search):fixes binary search iterative

Author: amejiarosario

src/runtimes/02-binary-search.js

@@ -18,9 +18,11 @@ function binarySearchRecursive(array, search, offset = 0) {
 
   if (current === search) {
     return offset + half;
-  } if (array.length === 1) {
+  }
+  if (array.length === 1) {
     return -1;
-  } if (search > current) {
+  }
+  if (search > current) {
     const right = array.slice(half);
     return binarySearchRecursive(right, search, offset + half);
   }
@@ -38,50 +40,24 @@ function binarySearchRecursive(array, search, offset = 0) {
  * @param {string|number} search value to search for
  */
 function binarySearchIterative(array, search) {
-  // console.log('binarySearchIterative', {array, search});
   let start = 0;
-  let end = array.length;
-  const half = () => parseInt((end - start) / 2, 10) + start;
+  let end = array.length - 1;
+  const half = () => start + parseInt((end - start) / 2, 10);
 
-  while (end - start > 0) {
+  while (start <= end) {
     const currentIndex = half();
     const current = array[currentIndex];
 
-    if (current === search) {
-      return currentIndex;
-    } if (search > current) {
-      start = currentIndex;
+    if (current === search) return currentIndex;
+
+    if (search > current) {
+      start = currentIndex + 1;
     } else if (search < current) {
-      end = currentIndex;
+      end = currentIndex - 1;
     }
   }
 
   return -1;
 }
 
-// const binarySearch = binarySearchRecursive;
-const binarySearch = binarySearchIterative;
-
-// function test() {
-//  const directory = ['Adrian', 'Bella', 'Charlotte', 'Daniel',
-//  'Emma', 'Hanna', 'Isabella', 'Jayden', 'Kaylee', 'Luke', 'Mia',
-//  'Nora', 'Olivia', 'Paisley', 'Riley', 'Thomas', 'Wyatt', 'Xander', 'Zoe'];
-//
-//   const assert = require('assert');
-//   assert.equal(binarySearch([], 'not found'), -1);
-//   assert.equal(binarySearch([1], 2), -1);
-//   assert.equal(binarySearch([1], 1), 0);
-//   assert.equal(binarySearch([1, 2, 3], 1), 0);
-//   assert.equal(binarySearch([1, 2, 3], 2), 1);
-//   assert.equal(binarySearch([1, 2, 3], 3), 2);
-//   assert.equal(binarySearch([1, 2, 3], 31), -1);
-//   assert.equal(binarySearch(directory, 'Adrian'), 0);
-//   assert.equal(binarySearch(directory, 'Hanna'), 5);
-//   assert.equal(binarySearch(directory, 'Zoe'), 18);
-//   assert.equal(binarySearch(directory, 'not found'), -1);
-// }
-
-// test();
-
-
-module.exports = { binarySearch, binarySearchIterative, binarySearchRecursive };
+module.exports = { binarySearchIterative, binarySearchRecursive };

src/runtimes/02-binary-search.spec.js

@@ -1,29 +1,39 @@
-const binarySearch = require('./02-binary-search').binarySearchRecursive;
+const {
+  binarySearchRecursive,
+  binarySearchIterative,
+} = require("./02-binary-search");
 
-describe('Binary Search', () => {
-  let array;
+const binarySearchImplementations = [
+  binarySearchRecursive,
+  binarySearchIterative,
+];
 
-  beforeEach(() => {
-    array = [7, 9, 13, 23];
-  });
+binarySearchImplementations.forEach((binarySearchImpl) => {
+  describe(binarySearchImpl.name, () => {
+    let array;
 
-  it('should find a middle element', () => {
-    expect(binarySearch(array, 9)).toEqual(1);
-  });
+    beforeEach(() => {
+      array = [7, 9, 13, 23];
+    });
 
-  it('should find an first element', () => {
-    expect(binarySearch(array, 7)).toEqual(0);
-  });
+    it("should find a middle element", () => {
+      expect(binarySearchImpl(array, 9)).toEqual(1);
+    });
 
-  it('should find the last element', () => {
-    expect(binarySearch(array, 23)).toEqual(3);
-  });
+    it("should find an first element", () => {
+      expect(binarySearchImpl(array, 7)).toEqual(0);
+    });
 
-  it('should not find an bigger element', () => {
-    expect(binarySearch(array, 9000)).toEqual(-1);
-  });
+    it("should find the last element", () => {
+      expect(binarySearchImpl(array, 23)).toEqual(3);
+    });
+
+    it("should not find an bigger element", () => {
+      expect(binarySearchImpl(array, 9000)).toEqual(-1);
+    });
 
-  it('should find a smaller element', () => {
-    expect(binarySearch(array, -9)).toEqual(-1);
+    it("should find a smaller element", () => {
+      expect(binarySearchImpl(array, -9)).toEqual(-1);
+    });
   });
 });