From 6b3be5c5c1023ff3c09587dd9928f1a71a7686b7 Mon Sep 17 00:00:00 2001
From: hemispherium <nkmr357@gmail.com>
Date: Thu, 25 Dec 2025 11:34:07 +0900
Subject: [PATCH] add files.

---
 0349-intersection-of-two-arrays/memo.md   | 13 +++++++++++++
 0349-intersection-of-two-arrays/step1.cpp | 19 +++++++++++++++++++
 0349-intersection-of-two-arrays/step2.cpp | 15 +++++++++++++++
 0349-intersection-of-two-arrays/step3.cpp | 15 +++++++++++++++
 4 files changed, 62 insertions(+)
 create mode 100644 0349-intersection-of-two-arrays/memo.md
 create mode 100644 0349-intersection-of-two-arrays/step1.cpp
 create mode 100644 0349-intersection-of-two-arrays/step2.cpp
 create mode 100644 0349-intersection-of-two-arrays/step3.cpp

diff --git a/0349-intersection-of-two-arrays/memo.md b/0349-intersection-of-two-arrays/memo.md
new file mode 100644
index 0000000..91cb5fa
--- /dev/null
+++ b/0349-intersection-of-two-arrays/memo.md
@@ -0,0 +1,13 @@
+### step1
+
+nums1とnums2をsetに入れて、制約である0-1000までの値の中で両方のsetに
+時間計算量はnums1, nums2の長さをN,MとしてO(NlogN + MlogM + 1000 * (logN + logM))になると思います。
+
+### step2
+
+step1のコードをGPTにより簡潔で高速なコードに修正してもらいました。
+時間計算量はO(N + M)に改善されると思います。
+
+### step3
+
+step2のコードを3回通すまで書き直し。
\ No newline at end of file
diff --git a/0349-intersection-of-two-arrays/step1.cpp b/0349-intersection-of-two-arrays/step1.cpp
new file mode 100644
index 0000000..bcec3df
--- /dev/null
+++ b/0349-intersection-of-two-arrays/step1.cpp
@@ -0,0 +1,19 @@
+class Solution {
+public:
+    vector<int> intersection(vector<int>& nums1, vector<int>& nums2) {
+        set<int> set1, set2;
+        for (int num1 : nums1) {
+            set1.insert(num1);
+        }
+        for (int num2 : nums2) {
+            set2.insert(num2);
+        }
+        vector<int> answer;
+        for (int i = 0; i <= 1000; i++) {
+            if (set1.contains(i) && set2.contains(i)) {
+                answer.push_back(i);
+            }
+        }
+        return answer;
+    }
+};
diff --git a/0349-intersection-of-two-arrays/step2.cpp b/0349-intersection-of-two-arrays/step2.cpp
new file mode 100644
index 0000000..5d77e83
--- /dev/null
+++ b/0349-intersection-of-two-arrays/step2.cpp
@@ -0,0 +1,15 @@
+class Solution {
+public:
+    vector<int> intersection(vector<int>& nums1, vector<int>& nums2) {
+        unordered_set<int> set_of_nums1(nums1.begin(), nums1.end());
+        unordered_set<int> answer;
+
+        for (int num2 : nums2) {
+            if (set_of_nums1.count(num2)) {
+                answer.insert(num2);
+            }
+        }
+
+        return vector<int>(answer.begin(), answer.end());
+    }
+};
diff --git a/0349-intersection-of-two-arrays/step3.cpp b/0349-intersection-of-two-arrays/step3.cpp
new file mode 100644
index 0000000..5d77e83
--- /dev/null
+++ b/0349-intersection-of-two-arrays/step3.cpp
@@ -0,0 +1,15 @@
+class Solution {
+public:
+    vector<int> intersection(vector<int>& nums1, vector<int>& nums2) {
+        unordered_set<int> set_of_nums1(nums1.begin(), nums1.end());
+        unordered_set<int> answer;
+
+        for (int num2 : nums2) {
+            if (set_of_nums1.count(num2)) {
+                answer.insert(num2);
+            }
+        }
+
+        return vector<int>(answer.begin(), answer.end());
+    }
+};