add: two sum solution

Author: Cyjin-jani

two-sum/Cyjin-jani.js

@@ -0,0 +1,14 @@
+const twoSum = function (nums, target) {
+  let memo = {};
+
+  for (let i = 0; i < nums.length; i++) {
+    let current = nums[i];
+    let needed = target - current;
+
+    if (needed in memo) {
+      return [memo[needed], i];
+    }
+
+    memo[current] = i;
+  }
+};