From ca9b8571aaf9fe50d2f115f19b5c698bd5a218d6 Mon Sep 17 00:00:00 2001
From: SinnoLn <ok373737@naver.com>
Date: Fri, 1 May 2026 18:47:13 +0900
Subject: [PATCH] =?UTF-8?q?[=EC=9D=B4=EC=A7=84=ED=9D=AC]=20Day01?=
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---
 .../Q1.java"                                  | 26 +++++++++++++++++++
 1 file changed, 26 insertions(+)
 create mode 100644 "leetcode3/\354\235\264\354\247\204\355\235\254/Q1.java"

diff --git "a/leetcode3/\354\235\264\354\247\204\355\235\254/Q1.java" "b/leetcode3/\354\235\264\354\247\204\355\235\254/Q1.java"
new file mode 100644
index 00000000..76985f05
--- /dev/null
+++ "b/leetcode3/\354\235\264\354\247\204\355\235\254/Q1.java"
@@ -0,0 +1,26 @@
+/*
+
+1. 아이디어 : 
+    1차(투포인터): 2차원 배열로 (값, 인덱스) 함께 저장 후 정렬하여 탐색. O(NlogN) + O(N)
+    2차(HashMap): 값:key, 인덱스:값 -> target을 만들기 위해 필요한 나머지 숫자 검색. O(N)
+
+2. 시간복잡도 : O(N)
+
+3. 자료구조/알고리즘 : HashMap
+
+ */
+
+class Solution {
+    public int[] twoSum(int[] nums, int target) {
+        Map<Integer,Integer> map = new HashMap<>();
+        
+        for(int i=0; i<nums.length; i++) {
+            int addNum = target-nums[i];
+
+            if(map.containsKey(addNum)) return new int[]{map.get(addNum), i};
+
+            map.put(nums[i], i);
+        }
+        return new int[]{-1,-1};
+    }
+}
\ No newline at end of file