java 在java中写一个函数来找到一个正整数N的二进制周期
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write a function in java to find the binary period of a positive integer N
提问by Hamzeen Hameem
A non-empty zero-indexed string S consisting of Q characters is given. The period of this string is the smallest
给出了一个由 Q 个字符组成的非空零索引字符串 S。这个字符串的周期是最小的
positive integer P such that:
正整数 P 使得：
P ≤ Q / 2 and S[K] = S[K+P] for 0 ≤ K < Q ? P.
P ≤ Q / 2 且 S[K] = S[K+P] 对于 0 ≤ K < Q ? P。
For example, 7 is the period of “pepsicopepsicopep”. A positive integer M is the binary period of a positive integer N if M is the period of the binary representation of N.
例如，7 是“pepsicopepsicopep”的时期。如果 M 是 N 的二进制表示的周期，则正整数 M 是正整数 N 的二进制周期。
For example, 1651has the binary representation of "110011100111". Hence, its binary period is 5. On the other hand, 102 does not have a binary period, because its binary representation is “1100110” and it does not have a period.
例如，1651的二进制表示为“110011100111”。因此，它的二进制周期是 5。另一方面，102没有二进制周期，因为它的二进制表示是“1100110”，它没有周期。
Consider above scenarios & write a function in Java which will accept an integer N as the parameter. Given a positive integer N, the function returns the binary period of N. The function should return ?1 if N does not have a binary period.
考虑上述场景并用 Java 编写一个函数，该函数将接受一个整数 N 作为参数。给定一个正整数 N，函数返回 N 的二进制周期。如果 N 没有二进制周期，函数应该返回 ?1。
Below I have included the solution I worked for it as well & I would like to know whether there exists any other better ways to solve it?
下面我也包括了我为它工作的解决方案，我想知道是否还有其他更好的方法来解决它？
回答by Hamzeen Hameem
public class BinaryPeriod {
public static void main(String[] args) {
System.out.println("\nEx1: " + getBinaryPeriodForInt(102));
System.out.println("\nEx2: " + getBinaryPeriodForInt(1651));
}
static int getBinaryPeriodForInt(int n) {
int[] d = new int[30];
int l = 0, res = -1;
while (n > 0) {
d[l] = n % 2;
n /= 2;
l++;
}
for (int p = 1; p < l; p++) {
if (p <= l / 2) {
boolean ok = true;
for (int i = 0; i < l - p; i++) {
if (d[i] != d[i + p]) {
ok = false;
break;
}
}
if (ok) {
res = p;
}
}
}
return res;
}
}
