[백준 20159] 동작 그만. 밑장 빼기냐? - 누적합

Author: HiiWee

hoseok/week81/Boj20159.java

@@ -0,0 +1,46 @@
+import java.io.*;
+import java.util.*;
+
+class Main {
+    public static void main(String[] args) throws Exception {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
+        int n = Integer.parseInt(br.readLine());
+        StringTokenizer st = new StringTokenizer(br.readLine());
+        long[] me = new long[n / 2];
+        long[] other = new long[n / 2];
+
+        for (int i = 0; i < n; i++) {
+            int number = Integer.parseInt(st.nextToken());
+            if (i % 2 == 0) {
+                me[i / 2] = number;
+                if (i / 2 > 0) {
+                    me[i / 2] += me[i / 2 - 1];
+                }
+            } else {
+                other[i / 2] = number;
+                if (i / 2 > 0) {
+                    other[i / 2] += other[i / 2 - 1];
+                }
+            }
+        }
+        if (n == 2) {
+            bw.write(Long.toString(Math.max(me[0], other[0])));
+            bw.flush();
+            bw.close();
+            return;
+        }
+
+        long max = Math.max(me[n / 2 - 1], other[n / 2 - 1]); // 밑장 안뻈을때 vs 내걸 첫번째 밑장 빼기
+        max = Math.max(me[0] + other[n / 2 - 2], max);
+        
+        for (int i = 1; i < n / 2; i++) {
+            max = Math.max(max, me[i - 1] + other[n / 2 - 1] - other[i - 1]); // 내걸 밑장빼기
+            max = Math.max(max, me[i] + other[n / 2 - 2] - other[i - 1]); // 상대방을 밑장빼기
+        }
+
+        bw.write(Long.toString(max));
+        bw.flush();
+        bw.close();
+    }
+}