[20250225] BOJ / P5 / 부분배열 고르기 / 권혁준

Author: oncsr

khj20006/202502/25 BOJ P5 부분배열 고르기.md

@@ -0,0 +1,89 @@
+```java
+
+import java.util.*;
+import java.io.*;
+
+
+class Main {
+	
+	// IO field
+	static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+	static BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
+	static StringTokenizer st;
+
+	static void nextLine() throws Exception {st = new StringTokenizer(br.readLine());}
+	static int nextInt() {return Integer.parseInt(st.nextToken());}
+	static long nextLong() {return Long.parseLong(st.nextToken());}
+	static void bwEnd() throws Exception {bw.flush();bw.close();}
+	
+	// Additional field
+
+    static int N;
+    static int[] r;
+    static long[] A, C;
+    static int[][] L;
+    static boolean[] V;
+	
+	public static void main(String[] args) throws Exception {
+		
+		ready();
+		solve();
+	
+		bwEnd();
+		
+	}
+	
+	static void ready() throws Exception{
+
+        N = Integer.parseInt(br.readLine());
+        
+        r = new int[N];
+        C = new long[N];
+        A = new long[N];
+        L = new int[N][2];
+        V = new boolean[N];
+        nextLine();
+        
+        
+        for(int i=0;i<N;i++) {
+            r[i] = i;
+            A[i] = nextLong();
+            C[i] = A[i];
+            L[i][0] = (int)A[i];
+            L[i][1] = i;
+        }
+		
+	}
+	
+	static void solve() throws Exception{
+		
+        Arrays.sort(L, (a,b) -> b[0]-a[0]);
+        
+        long ans = 0;
+        for(int[] now : L){
+            int v = now[0], i = now[1];
+            if(i>0 && V[i-1]){
+                int x = f(i), y = f(i-1);
+                C[x] += C[y];
+                r[y] = x;
+            }
+            if(i<N-1 && V[i+1]){
+                int x = f(i), y = f(i+1);
+                C[x] += C[y];
+                r[y] = x;
+            }
+            V[i] = true;
+            ans = Math.max(ans, v * C[f(i)]);
+            
+        }
+        bw.write(ans + "\n");
+		
+	}
+	
+	static int f(int x) {
+	    return x==r[x] ? x : (r[x]=f(r[x]));
+	}
+	
+}
+
+```