結果

問題 No.742 にゃんにゃんにゃん　猫の挨拶
ユーザー GrenacheGrenache
提出日時 2019-05-05 20:35:48
言語 Java21
(openjdk 21)
結果
AC  
実行時間 160 ms / 2,500 ms
コード長 6,201 bytes
コンパイル時間 5,016 ms
コンパイル使用メモリ 88,372 KB
実行使用メモリ 55,540 KB
最終ジャッジ日時 2023-09-08 06:57:48
合計ジャッジ時間 7,355 ms
ジャッジサーバーID
（参考情報） 		judge14 / judge15
このコードへのチャレンジ
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テストケース

テストケース表示
入力 結果 実行時間
実行使用メモリ
testcase_00 AC 54 ms
49,800 KB
testcase_01 AC 52 ms
50,308 KB
testcase_02 AC 52 ms
49,848 KB
testcase_03 AC 54 ms
50,060 KB
testcase_04 AC 55 ms
50,264 KB
testcase_05 AC 61 ms
50,656 KB
testcase_06 AC 65 ms
52,060 KB
testcase_07 AC 71 ms
52,224 KB
testcase_08 AC 76 ms
52,260 KB
testcase_09 AC 54 ms
50,296 KB
testcase_10 AC 52 ms
50,256 KB
testcase_11 AC 160 ms
55,540 KB
testcase_12 AC 150 ms
55,460 KB
testcase_13 AC 55 ms
49,996 KB
testcase_14 AC 54 ms
49,940 KB
testcase_15 AC 56 ms
50,144 KB
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ソースコード

diff # 

import java.io.*;
import java.util.*;


public class Main_yukicoder742 {

	private static Scanner sc;
	private static Printer pr;

	private static void solve() {
		int n = sc.nextInt();

		int[] m = new int[n];
		List<Integer> rl = new ArrayList<>();
		List<Integer> ll = new ArrayList<>();
		for (int i = 0; i < n; i++) {
			m[i] = sc.nextInt() - 1;
			if (m[i] >= i) {
				rl.add(i);
			} else {
				ll.add(i);
			}
		}
		// 右端の逆順
		Collections.sort(ll, (o1, o2) -> {
			if (o1 == o2) {
				Integer.compare(m[o2], m[o1]);
			}
			return Integer.compare(o2, o1);
		});
//		pr.println(rl);
//		pr.println(ll);

		long ans = 0;
		RSQ rsqr = new RSQ(n);
		for (int i : rl) {
			ans += rsqr.query(m[i], n);
			rsqr.add(m[i], 1);
		}
		RSQ rsql = new RSQ(n);
		for (int j : ll) {
			ans += rsql.query(0, m[j]);
			rsql.add(m[j], 1);
		}
		
//		pr.println(ans);

		// 右端の正順
		Collections.reverse(ll);
		RSQ rsq = new RSQ(n);
		int i = 0, size = rl.size();
		for (int j : ll) {
			while (i < size && rl.get(i) <= j) {
				rsq.add(m[rl.get(i++)], 1);
			}

			ans += rsq.query(m[j], n);
		}
		
		pr.println(ans);
	}
	
	// Range Sum Query by Segment Tree
	static class RSQ {
		int[] st;
		int n;

		RSQ(int n) {
			this.n = 1;
			while (this.n < n) {
				this.n *= 2;
			}
			st = new int[2 * this.n - 1];
		}

		// i:0-indexed
		void add(int i, int x) {
			i = n - 1 + i;
			st[i] += x;
			while (i > 0) {
				i = (i - 1) / 2;
				st[i] += x;
			}
		}

		// a, b:0-indexed
		// [a, b)
		int query(int a, int b) {
			return query(a, b, 0, 0, n);
		}

		private int query(int a, int b, int i, int l, int r) {
			if (a >= r || b <= l) {
				return 0;
			}
			if (a <= l && b >= r) {
				return st[i];
			}

			return query(a, b, i * 2 + 1, l, (l + r) / 2) + query(a, b, i * 2 + 2, (l + r) / 2, r);
		}
	}

	static class Pair implements Comparable<Pair> {
		int a;
		int b;

		Pair(int a, int b) {
			this.a = a;
			this.b = b;
		}

		@Override
		public int compareTo(Pair o) {
			if (a == o.a) {
				return Integer.compare(b, o.b);
			}

			return Integer.compare(a, o.a);
		}

		@Override
		public int hashCode() {
			return Integer.hashCode(a + b);
		}

		@Override
		public boolean equals(Object obj) {
			Pair o = (Pair) obj;
			return a == o.a && b == o.b;
		}

		@Override
		public String toString() {
			// [xxx, xxxx]
			StringBuilder stmp = new StringBuilder(32);
			stmp.append('[');
			stmp.append(a);
			stmp.append(',');
			stmp.append(' ');
			stmp.append(b);
			stmp.append(']');

			return stmp.toString();
		}
	}

	// ---------------------------------------------------
	public static void main(String[] args) {
		sc = new Scanner(System.in);
		pr = new Printer(System.out);
			
		solve();
			
		pr.close();
		sc.close();
	}

	static class Scanner {
		BufferedReader br;

		Scanner (InputStream in) {
			br = new BufferedReader(new InputStreamReader(in));
		}

		private boolean isPrintable(int ch) {
			return ch >= '!' && ch <= '~';
		}

		private boolean isCRLF(int ch) {
			return ch == '\n' || ch == '\r' || ch == -1;
		}

		private int nextPrintable() {
			try {
				int ch;
				while (!isPrintable(ch = br.read())) {
					if (ch == -1) {
						throw new NoSuchElementException();
					}
				}

				return ch;
			} catch (IOException e) {
				throw new NoSuchElementException();
			}
		}

		String next() {
			try {
				int ch = nextPrintable();
				StringBuilder sb = new StringBuilder();
				do {
					sb.appendCodePoint(ch);
				} while (isPrintable(ch = br.read()));

				return sb.toString();
			} catch (IOException e) {
				throw new NoSuchElementException();
			}
		}

		int nextInt() {
			try {
				// parseInt from Integer.parseInt()
				boolean negative = false;
				int res = 0;
				int limit = -Integer.MAX_VALUE;
				int radix = 10;

				int fc = nextPrintable();
				if (fc < '0') {
					if (fc == '-') {
						negative = true;
						limit = Integer.MIN_VALUE;
					} else if (fc != '+') {
						throw new NumberFormatException();
					}
					fc = br.read();
				}
				int multmin = limit / radix;

				int ch = fc;
				do {
					int digit = ch - '0';
					if (digit < 0 || digit >= radix) {
						throw new NumberFormatException();
					}
					if (res < multmin) {
						throw new NumberFormatException();
					}
					res *= radix;
					if (res < limit + digit) {
						throw new NumberFormatException();
					}
					res -= digit;

				} while (isPrintable(ch = br.read()));

				return negative ? res : -res;
			} catch (IOException e) {
				throw new NoSuchElementException();
			}
		}

		long nextLong() {
			try {
				// parseLong from Long.parseLong()
				boolean negative = false;
				long res = 0;
				long limit = -Long.MAX_VALUE;
				int radix = 10;

				int fc = nextPrintable();
				if (fc < '0') {
					if (fc == '-') {
						negative = true;
						limit = Long.MIN_VALUE;
					} else if (fc != '+') {
						throw new NumberFormatException();
					}
					fc = br.read();
				}
				long multmin = limit / radix;

				int ch = fc;
				do {
					int digit = ch - '0';
					if (digit < 0 || digit >= radix) {
						throw new NumberFormatException();
					}
					if (res < multmin) {
						throw new NumberFormatException();
					}
					res *= radix;
					if (res < limit + digit) {
						throw new NumberFormatException();
					}
					res -= digit;

				} while (isPrintable(ch = br.read()));

				return negative ? res : -res;
			} catch (IOException e) {
				throw new NoSuchElementException();
			}
		}

		float nextFloat() {
			return Float.parseFloat(next());
		}

		double nextDouble() {
			return Double.parseDouble(next());
		}

		String nextLine() {
			try {
				int ch;
				while (isCRLF(ch = br.read())) {
					if (ch == -1) {
						throw new NoSuchElementException();
					}
				}
				StringBuilder sb = new StringBuilder();
				do {
					sb.appendCodePoint(ch);
				} while (!isCRLF(ch = br.read()));

				return sb.toString();
			} catch (IOException e) {
				throw new NoSuchElementException();
			}
		}

		void close() {
			try {
				br.close();
			} catch (IOException e) {
//				throw new NoSuchElementException();
			}
		}
	}

	static class Printer extends PrintWriter {
		Printer(OutputStream out) {
			super(out);
		}
	}
}
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