add binary search tree

Author: sangtrandev00

src/algorithm/searching/binary-search.test.ts

@@ -0,0 +1,37 @@
+import { describe, it, expect } from "bun:test";
+import { binarySearch } from "./binary-search";
+
+describe('Binary Search Function', () => {
+    const sortedArray = [0, 1, 2, 4, 5, 6, 44, 63, 87, 99, 283];
+
+    it('should return the index of the element when it exists', () => {
+        const result = binarySearch(sortedArray, 5);
+        expect(result).toBe(4); // 5 is at index 4
+    });
+
+    it('should return -1 when the element does not exist', () => {
+        const result = binarySearch(sortedArray, 100);
+        expect(result).toBe(-1); // 100 is not in the array
+    });
+
+    it('should return the index of the first element', () => {
+        const result = binarySearch(sortedArray, 0);
+        expect(result).toBe(0); // 0 is at index 0
+    });
+
+    it('should return the index of the last element', () => {
+        const result = binarySearch(sortedArray, 283);
+        expect(result).toBe(10); // 283 is at index 10
+    });
+
+    it('should return -1 for an empty array', () => {
+        const result = binarySearch([], 1);
+        expect(result).toBe(-1); // Searching in an empty array
+    });
+
+    it('should handle an array with duplicate elements', () => {
+        const arrayWithDuplicates = [1, 1, 1, 1, 1, 2, 3, 4, 5];
+        const result = binarySearch(arrayWithDuplicates, 1);
+        expect(result).toBe(0); // The first occurrence of 1 is at index 0
+    });
+});

src/algorithm/searching/binary-search.ts

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+// Function này chưa handle trường hợp duplicate element trong array!
+export function binarySearch(array: number[], target: number): number {
+    let left = 0;
+    let right = array.length - 1;
+    while (left <= right) {
+        const middle = Math.floor((left + right) / 2);
+        if (array[middle] === target) {
+            return middle
+        } else if (array[middle] < target) {
+            // Target nằm bên phải
+            left = middle + 1
+        } else if (array[middle] > target) {
+            // Target nằm bên trái
+            right = middle - 1
+        }
+    }
+    return -1
+}
+
+console.log(binarySearch([1, 2, 3, 4, 5, 6, 7, 8, 9, 10], 5));