add: two-sum

Author: Yongseok-Choi-dev

two-sum/YoungSeok-Choi.java

@@ -0,0 +1,20 @@
+// time complexity: O(n);
+
+// 특정 nums[i] 가 target이 되기위한 보수 (target - nums[i])를 candidate Map에서 찾으면 종료
+class Solution {
+    public int[] twoSum(int[] nums, int target) {
+        Map<Integer, Integer> candidate = new HashMap<>();
+
+        for(int i = 0; i < nums.length; i++) {
+
+            int diff = target - nums[i];
+
+            if(candidate.containsKey(diff)) {
+                return new int[] { candidate.get(diff), i };
+            }
+
+            candidate.put(nums[i], i);
+        }
+        return new int[0];
+    }
+}