#572571 (Java21) No.1271 初めての級数

• 問題: No.1271 初めての級数
• ユーザー: ywmt
• 提出日時: 2020-10-30 21:26:21
• 言語: Java21 (openjdk 21)
• 結果: AC
• 実行時間: 46 ms / 2,000 ms
• コード長: 4,369 bytes
• コンパイル時間: 2,632 ms
• コンパイル使用メモリ: 74,296 KB
• 実行使用メモリ: 49,488 KB
• 最終ジャッジ日時: 2023-09-29 04:45:34
• 合計ジャッジ時間: 3,628 ms
• ジャッジサーバーID （参考情報）: judge15 / judge12

入力	結果	実行時間; 実行使用メモリ
testcase_00	AC	44 ms; 49,168 KB
testcase_01	AC	44 ms; 49,176 KB
testcase_02	AC	44 ms; 48,948 KB
testcase_03	AC	44 ms; 49,124 KB
testcase_04	AC	43 ms; 49,480 KB
testcase_05	AC	44 ms; 49,000 KB
testcase_06	AC	44 ms; 48,908 KB
testcase_07	AC	46 ms; 49,196 KB
testcase_08	AC	44 ms; 49,024 KB
testcase_09	AC	46 ms; 49,128 KB
testcase_10	AC	46 ms; 49,360 KB
testcase_11	AC	45 ms; 49,488 KB
testcase_12	AC	45 ms; 49,096 KB

ソースコード

import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.InputMismatchException;
import java.util.NoSuchElementException;

public class Main {
    static PrintWriter out;
    static InputReader ir;

    static void solve() {
        int k = ir.nextInt();
        if (k == 0) {
            out.println(Math.PI * Math.PI / 6);
            return;
        }
        double res = 0.0;
        for (int i = 1; i <= k; i++)
            res += 1.0 / i / k;
        out.println(res);
    }

    public static void main(String[] args) {
        ir = new InputReader(System.in);
        out = new PrintWriter(System.out);
        solve();
        out.flush();
    }

    static class InputReader {

        private InputStream in;
        private byte[] buffer = new byte[1024];
        private int curbuf;
        private int lenbuf;

        public InputReader(InputStream in) {
            this.in = in;
            this.curbuf = this.lenbuf = 0;
        }

        public boolean hasNextByte() {
            if (curbuf >= lenbuf) {
                curbuf = 0;
                try {
                    lenbuf = in.read(buffer);
                } catch (IOException e) {
                    throw new InputMismatchException();
                }
                if (lenbuf <= 0)
                    return false;
            }
            return true;
        }

        private int readByte() {
            if (hasNextByte())
                return buffer[curbuf++];
            else
                return -1;
        }

        private boolean isSpaceChar(int c) {
            return !(c >= 33 && c <= 126);
        }

        private void skip() {
            while (hasNextByte() && isSpaceChar(buffer[curbuf]))
                curbuf++;
        }

        public boolean hasNext() {
            skip();
            return hasNextByte();
        }

        public String next() {
            if (!hasNext())
                throw new NoSuchElementException();
            StringBuilder sb = new StringBuilder();
            int b = readByte();
            while (!isSpaceChar(b)) {
                sb.appendCodePoint(b);
                b = readByte();
            }
            return sb.toString();
        }

        public int nextInt() {
            if (!hasNext())
                throw new NoSuchElementException();
            int c = readByte();
            while (isSpaceChar(c))
                c = readByte();
            boolean minus = false;
            if (c == '-') {
                minus = true;
                c = readByte();
            }
            int res = 0;
            do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res = res * 10 + c - '0';
                c = readByte();
            } while (!isSpaceChar(c));
            return (minus) ? -res : res;
        }

        public long nextLong() {
            if (!hasNext())
                throw new NoSuchElementException();
            int c = readByte();
            while (isSpaceChar(c))
                c = readByte();
            boolean minus = false;
            if (c == '-') {
                minus = true;
                c = readByte();
            }
            long res = 0;
            do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res = res * 10 + c - '0';
                c = readByte();
            } while (!isSpaceChar(c));
            return (minus) ? -res : res;
        }

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

        public int[] nextIntArray(int n) {
            int[] a = new int[n];
            for (int i = 0; i < n; i++)
                a[i] = nextInt();
            return a;
        }

        public long[] nextLongArray(int n) {
            long[] a = new long[n];
            for (int i = 0; i < n; i++)
                a[i] = nextLong();
            return a;
        }

        public char[][] nextCharMap(int n, int m) {
            char[][] map = new char[n][m];
            for (int i = 0; i < n; i++)
                map[i] = next().toCharArray();
            return map;
        }
    }

    static void tr(Object... o) {
        System.err.println(Arrays.deepToString(o));
    }
}