📦 NEW: Solve Array Easy problem - Two sum

Author: ManiruzzamanAkash

README.md

@@ -3,5 +3,5 @@ Solve [LeetCode](https://leetcode.com) problems using JavaScript By Topic wise w
 
 ---
 
-## Array Problems -
+## Array Problems Solution -
 1. [Two Sum](https://leetcode.com/problems/two-sum/) - [Solution](https://github.com/ManiruzzamanAkash/LeetCode-In-JS/blob/main/two-sum/)

two-sum/index.js

@@ -0,0 +1,26 @@
+/**
+ * Two sum Problem leetcode.
+ *
+ * @param {number[]} nums
+ * @param {number} target
+ *
+ * @return {number[]}
+ */
+var twoSum = function(nums, target) {
+  const hashmap = {};
+  for (let i = 0; i < nums.length; i++) {
+    const diff = target - nums[i];
+
+    // If the difference is in the hashmap, return the indices.
+    if (diff in hashmap) { // or, hashmap[diff] !== undefined
+      return [hashmap[diff], i];
+    }
+
+    // Otherwise, add the current number to the hashmap.
+    hashmap[nums[i]] = i;
+  }
+
+  return [];
+};
+
+module.exports = twoSum;

two-sum/index.test.js

@@ -0,0 +1,17 @@
+const twoSum = require("./index");
+
+test("[2, 7, 11, 15] array and target 9 would result [0, 1]", () => {
+  expect(twoSum([2, 7, 11, 15], 9)).toStrictEqual([0, 1]);
+});
+
+test("[3, 3] array and target 6 would result [0, 1]", () => {
+  expect(twoSum([3, 3], 6)).toStrictEqual([0, 1]);
+});
+
+test("[3, 2, 4] array and target 6 would result [1, 2]", () => {
+  expect(twoSum([3, 2, 4], 6)).toStrictEqual([1, 2]);
+});
+
+test("[3, 2, 3] array and target 6 would result [0, 2]", () => {
+  expect(twoSum([3, 2, 3], 6)).toStrictEqual([0, 2]);
+});