two-sum

Author: jun0811

two-sum/jun0811.js

@@ -0,0 +1,26 @@
+// Time Complexity : O(N^2)
+
+var twoSum = function (nums, target) {
+  const l = nums.length;
+  for (let i = 0; i < l; i++) {
+    for (let j = i + 1; j < l; j++) {
+      const value = nums[i] + nums[j];
+      if (value == target) return [i, j];
+    }
+  }
+};
+
+// Time Complexity : O(N)
+
+var twoSum = function (nums, target) {
+  const Map = {};
+
+  nums.forEach((num, idx) => {
+    Map[num] = idx;
+  });
+
+  for (const idx in nums) {
+    const value = target - nums[idx];
+    if (Map[value] >= 0 && Map[value] != idx) return [+idx, Map[value]];
+  }
+};