4차시 업로드

YIM2UL2ET/README.md

@@ -4,5 +4,6 @@
 |:----:|:---------:|:----:|:-----:|:----:|
 | 1차시 | 2024.02.12 |  그리디  | [BOJ 18310](https://www.acmicpc.net/problem/18310)  | [BOJ 18310 풀이](https://github.com/AlgoLeadMe/AlgoLeadMe-7/pull/3) |
 | 2차시 | 2024.02.15 |  그리디  | [BOJ 1263](https://www.acmicpc.net/problem/1263)  | [BOJ 1449 풀이](https://github.com/AlgoLeadMe/AlgoLeadMe-7/pull/7) |
-| 3차시 | 2024.02.18 |  자료구조  | [BOJ 2504](https://www.acmicpc.net/problem/2504)  | [BOJ 2504 풀이](https://github.com/AlgoLeadMe/AlgoLeadMe-7/pull/9) |
+| 3차시 | 2024.02.18 |  스택  | [BOJ 2504](https://www.acmicpc.net/problem/2504)  | [BOJ 2504 풀이](https://github.com/AlgoLeadMe/AlgoLeadMe-7/pull/9) |
+| 4차시 | 2024.02.21 |  덱  | [BOJ 1021](https://www.acmicpc.net/problem/1021)  | [BOJ 1021 풀이](https://github.com/AlgoLeadMe/AlgoLeadMe-7/pull/12) |
 ---

YIM2UL2ET/덱/4차시 - BOJ 1021.cpp

@@ -0,0 +1,45 @@
+#include <iostream>
+#include <algorithm>
+#include <deque>
+
+int main(void)
+{
+    int n, m, k, idx, result;
+    std::deque <int> dq;
+
+    std::cin >> n >> m;
+    for (int i = 0; i < n;) {
+        dq.push_back(++i);
+    }
+
+    result = 0;
+    for (int i = 0; i < m; i++) {
+        std::cin >> k;
+
+        std::deque <int> :: iterator iter;
+        iter = std::find(dq.begin(), dq.end(), k);
+        idx = std::distance(dq.begin(), iter);
+
+        if (idx < dq.size() - idx) {
+            result += idx;
+            for (int j = 0; j < idx; j++) {
+                int temp = dq.front();
+                dq.pop_front();
+                dq.push_back(temp);
+            }
+        }
+        else {
+            result += dq.size() - idx;
+            for (int j = 0; j < dq.size() - idx; j++) {
+                int temp = dq.back();
+                dq.pop_back();
+                dq.push_front(temp);
+            }
+        }
+
+        dq.pop_front();
+    }
+
+    std::cout << result;
+    return 0;   
+}