Java面試--google 筆試題
阿新 • • 發佈：2018-12-12
google 筆試題
Beautiful Numbers
分析：
程式碼實現：
BeautifulNumber.java
package interview.google; import java.io.BufferedReader; import java.io.InputStreamReader; import java.util.Scanner; public class BeautifulNumber { public static void main(String[] args) { Scanner in = new Scanner( new BufferedReader(new InputStreamReader(System.in))); int cases = in.nextInt(); for (int i = 1; i <= cases; ++i) { long n = in.nextLong(); System.out.println("Case #" + i + ": " + beautiful(n)); } } private static long beautiful(long n) { for (long radix = 2; radix < n; radix++) { if (isBeautiful(n, radix)) { return radix; } } throw new IllegalStateException("Should not reach here."); } private static boolean isBeautiful(long n, long radix) { while (n > 0) { if (n % radix != 1) { return false; } n /= radix; } return true; } }
輸出：
解大資料集
程式碼：BeautifulNumberLarge.java
package interview.google; import java.io.BufferedReader; import java.io.InputStreamReader; import java.util.Scanner; public class BeautifulNumberLarge { public static void main(String[] args) { Scanner in = new Scanner( new BufferedReader(new InputStreamReader(System.in))); int cases = in.nextInt(); for (int i = 1; i <= cases; ++i) { long n = in.nextLong(); System.out.println("Case #" + i + ": " + beautiful(n)); } } private static long beautiful(long n) { for (int bits = 64; bits >= 2; bits--) { long radix = getRadix(n, bits); if (radix != -1) { return radix; } } throw new IllegalStateException("Should not reach here."); } /** * Gets radix so that n is 111...1 (bits 1 in total) in that * radix. * * @return the radix. -1 if there's no such radix. */ private static long getRadix(long n, int bits) { long minRadix = 2; long maxRadix = n; while (minRadix < maxRadix) { long m = minRadix + (maxRadix - minRadix) / 2; long t = convert(m, bits); if (t == n) { return m; } else if (t < n) { minRadix = m + 1; } else { maxRadix = m; } } return -1; } /** * Returns the value of 111...1 (bits 1 in total) in radix. */ private static long convert(long radix, int bits) { long component = 1; long sum = 0; for (int i = 0; i < bits; i++) { if (Long.MAX_VALUE - sum < component) { sum = Long.MAX_VALUE; } else { sum += component; } if (Long.MAX_VALUE / component < radix) { component = Long.MAX_VALUE; } else { component *= radix; } } return sum; } }
輸出：（部分）
驗證正確
