Merge pull request #9 from anasmak04/master

mehediislamripon · web-flow · commit 644557f3fb1c · 2022-11-29T20:32:06.000+06:00
add binary search
diff --git a/README.md b/README.md
@@ -48,6 +48,7 @@
 | Problem - 44  | [ swap ](https://github.com/anasmak04/Problem-solving-with-JavaScript/blob/master/problem-44.js) |
 | Problem - 45  | [ max two numbers ](https://github.com/anasmak04/Problem-solving-with-JavaScript/blob/master/problem-45.js) |
 | Problem - 46  | [ Sort an Array without using any built-in functions ](https://github.com/anasmak04/Problem-solving-with-JavaScript/blob/master/problem-46.js) |
+| Problem - 47  | [ Binary Search ](https://github.com/anasmak04/Problem-solving-with-JavaScript/blob/master/problem-47.js) |
 
 
-<!-- | Problem - 47  |   | -->
+<!-- | Problem - 48  |   | -->
diff --git a/problem-47.js b/problem-47.js
@@ -0,0 +1,35 @@
+// Given an array of integers nums which is sorted in ascending order,
+//  and an integer target, write a function to search target in nums.
+//   If target exists, then return its index. Otherwise, return -1.
+// You must write an algorithm with O(log n) runtime complexity.
+
+
+let search = function (nums, target) {
+    let array = nums.sort(function (a, b) { return a - b });
+    let firstIndex = 0;
+    let lastIndex = array.length - 1;
+    while (firstIndex <= lastIndex) {
+        let middleIndex = Math.floor((firstIndex + lastIndex) / 2);
+        if (target == array[middleIndex]) {
+            return middleIndex
+        }
+        if (target < array[middleIndex]) {
+            lastIndex = middleIndex - 1;
+        }
+        else {
+            firstIndex = middleIndex + 1;
+        }
+    }
+    return -1
+};
+
+// Example 1:
+
+// Input: nums = [-1,0,3,5,9,12], target = 9
+// Output: 4
+// Explanation: 9 exists in nums and its index is 4
+// Example 2:
+
+// Input: nums = [-1,0,3,5,9,12], target = 2
+// Output: -1
+// Explanation: 2 does not exist in nums so return -1
