From b9d7d97861450f8f8e81f77e98ff6d8431f4216b Mon Sep 17 00:00:00 2001
From: "YeJun, Jung" <yejun614@naver.com>
Date: Sun, 25 Jan 2026 19:17:18 +0900
Subject: [PATCH] add p42862 solutions

---
 problems/programmers/others/p42862/main.cpp  | 35 ++++++++
 problems/programmers/others/p42862/main2.cpp | 89 ++++++++++++++++++++
 problems/programmers/others/p42862/main3.cpp | 64 ++++++++++++++
 3 files changed, 188 insertions(+)
 create mode 100644 problems/programmers/others/p42862/main.cpp
 create mode 100644 problems/programmers/others/p42862/main2.cpp
 create mode 100644 problems/programmers/others/p42862/main3.cpp

diff --git a/problems/programmers/others/p42862/main.cpp b/problems/programmers/others/p42862/main.cpp
new file mode 100644
index 0000000..964590d
--- /dev/null
+++ b/problems/programmers/others/p42862/main.cpp
@@ -0,0 +1,35 @@
+/*
+ * (42862) 체육복
+ * https://school.programmers.co.kr/learn/courses/30/lessons/42862
+ */
+
+#include <iostream>
+
+#include <vector>
+using namespace std;
+
+int solution(int n, vector<int> lost, vector<int> reserve) {
+  int answer = n;
+
+  vector<int> students(n + 2, 1);
+  for (int i : reserve) students[i] = 2;
+  for (int i : lost) --students[i];
+
+  for (int s = 1; s <= n; ++s) {
+    if (students[s] > 0) continue;
+    if (students[s - 1] > 1) --students[s - 1];
+    else if (students[s + 1] > 1) --students[s + 1];
+    else --answer;
+  }
+  return answer;
+}
+
+int main() {
+  cout << "#1 " << solution(5, {2, 4}, {1, 3, 5}) << endl; // 5
+  cout << "#2 " << solution(5, {2, 4}, {3}) << endl; // 4
+  cout << "#3 " << solution(3, {3}, {1}) << endl; // 2
+  cout << "#4 " << solution(5, {4, 2}, {3, 5}) << endl; // 5
+
+  return 0;
+}
+
diff --git a/problems/programmers/others/p42862/main2.cpp b/problems/programmers/others/p42862/main2.cpp
new file mode 100644
index 0000000..54dd8aa
--- /dev/null
+++ b/problems/programmers/others/p42862/main2.cpp
@@ -0,0 +1,89 @@
+/*
+ * (42862) 체육복
+ * https://school.programmers.co.kr/learn/courses/30/lessons/42862
+ */
+
+#include <iostream>
+
+#include <vector>
+#include <algorithm>
+using namespace std;
+
+// A, B의 교집합
+vector<int> intersection(vector<int> A, vector<int> B) {
+  vector<int> result;
+
+  for (int a : A) for (int b : B)
+      if (a == b) result.push_back(a);
+
+  return result;
+}
+
+// target에서 remove_items 요소 삭제
+vector<int> remove_all(vector<int> remove_items, vector<int> target) {
+  vector<int> result;
+
+  for (int item : target) {
+    result.push_back(item);
+
+    for (int check : remove_items) {
+      if (item == check) {
+        result.pop_back();
+        break;
+      }
+    }
+  }
+
+  return result;
+}
+
+int solution(int n, vector<int> lost, vector<int> reserve) {
+  // lost, reserve 교집합 산출 후 제거
+  vector<int> common = intersection(lost, reserve);
+  lost = remove_all(common, lost);
+  reserve = remove_all(common, reserve);
+
+  // 오름차순 정렬
+  sort(lost.begin(), lost.end());
+  sort(reserve.begin(), reserve.end());
+
+  // 일단 (전체 학생 수) - (도둑 맞은 학생) 으로 answer 초기화
+  // 여기서 도둑 맞은 학생이라도 여분이 있다면 수업에 참가할 수 있음에 주의
+  int answer = n - lost.size();
+
+  vector<int> check_arr(2);
+  for (int student : lost) {
+    // 도둑 맞은 학생은 앞, 뒤의 학생에게 운동복을 빌릴 수 있다
+    check_arr[0] = student - 1;
+    check_arr[1] = student + 1;
+
+    for (int check : check_arr) {
+      // reserve 에서 check 값 찾기
+      auto iter = reserve.begin();
+      for (; iter != reserve.end(); ++iter) {
+        if (check == *iter) {
+          break;
+        }
+      }
+
+      // reserve에 check 값이 존재한다면
+      if (iter != reserve.end()) {
+        reserve.erase(iter);
+        ++answer; // answer 수정
+        break;
+      }
+    }
+  }
+
+  return answer;
+}
+
+int main() {
+  cout << "#1 " << solution(5, {2, 4}, {1, 3, 5}) << endl; // 5
+  cout << "#2 " << solution(5, {2, 4}, {3}) << endl; // 4
+  cout << "#3 " << solution(3, {3}, {1}) << endl; // 2
+  cout << "#4 " << solution(5, {4, 2}, {3, 5}) << endl; // 5
+
+  return 0;
+}
+
diff --git a/problems/programmers/others/p42862/main3.cpp b/problems/programmers/others/p42862/main3.cpp
new file mode 100644
index 0000000..f583112
--- /dev/null
+++ b/problems/programmers/others/p42862/main3.cpp
@@ -0,0 +1,64 @@
+/*
+ * (42862) 체육복
+ * https://school.programmers.co.kr/learn/courses/30/lessons/42862
+ */
+
+#include <iostream>
+
+#include <string>
+#include <vector>
+#include <set>
+#include <algorithm>
+
+using namespace std;
+
+int solution(int n, vector<int> lost, vector<int> reserve) {
+  // lost, reserve를 set 컨테이너로 복사(정렬 및 삭제연산 유리함)
+  set<int> lost_set(lost.begin(), lost.end());
+  set<int> reserve_set(reserve.begin(), reserve.end());
+
+  // lost, reserve 교집합 찾기
+  vector<int> common;
+
+  // set_intersection 함수는 호출전에 대상 배열들이 정렬되어 있어야 한다
+  set_intersection(
+    lost_set.begin(), lost_set.end(), reserve_set.begin(), reserve_set.end(),
+    back_inserter(common));
+
+  // 교집합 삭제
+  for (int it : common) {
+    lost_set.erase(it);
+    reserve_set.erase(it);
+  }
+
+  // 일단 (전체 학생 수) - (도둑 맞은 학생) 으로 answer 초기화
+  // 여기서 도둑 맞은 학생이라도 여분이 있다면 수업에 참가할 수 있음에 주의
+  int answer = n - lost_set.size();
+
+  vector<int> check_arr(2);
+  for (int student : lost_set) {
+    // 도둑 맞은 학생은 앞, 뒤의 학생에게 운동복을 빌릴 수 있다
+    check_arr[0] = student - 1;
+    check_arr[1] = student + 1;
+
+    for (int check : check_arr) {
+      if (auto iter = reserve_set.find(check); iter != reserve_set.end()) {
+        reserve_set.erase(iter);
+        ++answer; // answer 수정
+        break;
+      }
+    }
+  }
+
+  return answer;
+}
+
+int main() {
+  cout << "#1 " << solution(5, {2, 4}, {1, 3, 5}) << endl; // 5
+  cout << "#2 " << solution(5, {2, 4}, {3}) << endl; // 4
+  cout << "#3 " << solution(3, {3}, {1}) << endl; // 2
+  cout << "#4 " << solution(5, {4, 2}, {3, 5}) << endl; // 5
+
+  return 0;
+}
+