[WonYeong] Week3

two-sum/dalpang81.java

@@ -0,0 +1,23 @@
+/*
+* 시간복잡도 : O(n)
+* 공간복잡도 : O(n)
+* */
+
+import java.util.HashMap;
+import java.util.Map;
+
+class Solution {
+    public int[] twoSum(int[] nums, int target) {
+        Map<Integer, Integer> map = new HashMap<>();
+
+        for (int i = 0; i < nums.length; i++) {
+            int complement = target - nums[i];
+
+            if (map.containsKey(complement)) {
+                return new int[] { map.get(complement), i };
+            }
+            map.put(nums[i], i);
+        }
+        return null;
+    }
+}