Add week 3 solutions: two-sum

Author: gitsunmin

two-sum/gitsunmin.ts

@@ -0,0 +1,16 @@
+/**
+ * https://leetcode.com/problems/two-sum
+ * time complexity : O(n)
+ * space complexity : O(n)
+ */
+function twoSum(nums: number[], target: number): number[] {
+    const m = new Map<number, number>();
+
+    for (let i = 0; i < nums.length; i++) {
+        if (m.has(nums[i]))
+            return [m.get(nums[i]), i];
+        m.set(target - nums[i], i);
+    }
+
+    return [-1, -1];
+};