[20250318] BOJ / P5 / 빌보의 생일 / 권혁준

khj20006/202503/18 BOJ P5 빌보의 생일.md

@@ -0,0 +1,87 @@
+```java
+
+import java.util.*;
+import java.io.*;
+
+class SegTree{
+	int[] tree;
+	SegTree(int size){
+		tree = new int[size*4+1];
+	}
+
+	void upt(int s, int e, int i, int n) {
+		if(s==e) {
+			tree[n] = 1;
+			return;
+		}
+		int m=(s+e)>>1;
+		if(i<=m) upt(s,m,i,n*2);
+		else upt(m+1,e,i,n*2+1);
+		tree[n] = tree[n*2] + tree[n*2+1];
+	}
+
+	int find(int s, int e, int l, int r, int n) {
+		if(l>r || l>e || r<s) return 0;
+		if(l<=s && e<=r) return tree[n];
+		int m=(s+e)>>1;
+		return find(s,m,l,r,n*2) + find(m+1,e,l,r,n*2+1);
+	}
+}
+
+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 = new StringTokenizer("");
+
+	static void nextLine() throws Exception {st = new StringTokenizer(br.readLine());}
+	static String nextToken() throws Exception {
+		if(!st.hasMoreTokens()) nextLine();
+		return st.nextToken();
+	}
+	static int nextInt() throws Exception { return Integer.parseInt(nextToken()); }
+	static long nextLong() throws Exception { return Long.parseLong(nextToken()); }
+	static void bwEnd() throws Exception {bw.flush();bw.close();}
+
+	// Additional field
+
+	static int N;
+	static SegTree seg;
+	static TreeMap<String, Integer> T;
+
+	public static void main(String[] args) throws Exception {
+
+		for(N = nextInt();N != 0;N = nextInt()) {
+
+			ready();
+			solve();
+		}
+
+		bwEnd();
+
+	}
+
+	static void ready() throws Exception{
+
+		T = new TreeMap<>();
+		seg = new SegTree(N);
+		for(int i=1;i<=N;i++) T.put(nextToken(), i);
+
+	}
+
+	static void solve() throws Exception{
+
+		long ans = 0;
+		for(int i=1;i<=N;i++) {
+			int x = T.get(nextToken());
+			ans += seg.find(1, N, x, N, 1);
+			seg.upt(1,N,x,1);
+		}
+		bw.write(ans + "\n");
+
+	}
+
+}
+
+```