[ADD] BOJ 2559 수열

- 투 포인터

Author: tdm1223

acmicpc.net/README.md

@@ -590,6 +590,7 @@
 |  47  |      [키 큰 사람](https://www.acmicpc.net/problem/11292)       | [cpp](source/11292.cpp)  |  48  |          [좌표 압축](https://www.acmicpc.net/problem/18870)           | [cpp](source/18870.cpp) |
 |  49  |       [두 수의 합](https://www.acmicpc.net/problem/3273)       |  [cpp](source/3273.cpp)  |  50  |         [게으른 백곰](https://www.acmicpc.net/problem/10025)          | [cpp](source/10025.cpp) |
 |  51  |          [약속](https://www.acmicpc.net/problem/1183)          |  [cpp](source/1183.cpp)  |  52  |       [효정과 새 모니터](https://www.acmicpc.net/problem/20949)       | [cpp](source/20949.cpp) |
+|  53  |          [수열](https://www.acmicpc.net/problem/2559)          |  [cpp](source/2559.cpp)  |      |                                                                       |                         |
 
 </details>
 

acmicpc.net/source/2559.cpp

@@ -0,0 +1,39 @@
+// 2559. 수열
+// 2022.05.01
+// 투 포인터
+#include<iostream>
+#include<algorithm>
+
+using namespace std;
+
+int arr[100000];
+
+int main()
+{
+    int n, k;
+    cin >> n >> k;
+
+    for (int i = 0; i < n; i++)
+    {
+        cin >> arr[i];
+    }
+
+    int sum = 0;
+    int idx = 0;
+    int ans = -987654321;
+    for (int i = 0; i < n; i++)
+    {
+        sum += arr[i];
+        idx++;
+        if (idx == k)
+        {
+            ans = max(ans, sum);
+
+            // two pointer
+            sum -= arr[i - k + 1];
+            idx--;
+        }
+    }
+    cout << ans << endl;
+    return 0;
+}